FLOOR INFECTION:
This is done by simply playing Sound Voltex. After each credit, if there are songs to unlock on other games, the list will show up. The IIDX unlocks will show up as for Pendual, but they can still be unlocked for copula (this selection was revived at the same time copula was released). To obtain both IIDX unlocks, the meter must be filled twice (18% per credit for the first one, and 16% per credit on the second, this appears to not be affected by failing out early). Once the meter is filled, spare points can be used for any other selection. Today is effectively the last day for the IIDX songs, though they may come back later (this is the second time around for them, and there's at least one selection that has been back FIVE TIMES).

Kaitsuu! Tokotoko line (開通！とことこライン):

This runs for everyone using a pass (there's no opting out of it!). Railroad materials are awarded after every song (25 for Standard/Class/HAZARD mode, 33 for Step Up mode, 50 for Free Mode), regardless of pass/fail and after the credit is done, the player will be prompted to choose a course to build a railroad on. Initially, only the first one is available, and must be completed to open the others.

When a course is picked, a card shuffle shows up, with cards indicating one of four characters (it is possible for one character to appear on multiple cards). As one might expect, the more stars on the card, the better the effect. The cards will be shuffled, and one is picked with the white keys. If you have purchased Rainbow Tickets on the website, they can also be used here to reveal other cards (2 tickets gets you one more card flip, and after that, 3 tickets will give you all four cards).

In addition, you can specify up to 3 additional players on the event website (http://p.eagate.573.jp/game/2dx/23/p/djdata/tokotoko_friend_search.html for the actual search) to contribute a small amount (this won't affect the unlocking event for those other players). It's not much, but every little bit helps. The three search buttons on the bottom of the page are: Players who have you on their train, players who last played at your registered location, and players who have the same registered location. Also, by playing a song from each version folder (save Substream), a special tool is earned toward increasing the build rate. If all 23 tools are collected, the build rate is 1.5x.

Completing a railroad course will bring up an unlock prompt with four songs in it. Choose one of these four. As other railroads are finished, the same list appears, minus songs already unlocked.

Courses can be revisited to improve them. All courses except for course 1 have multiple stations. Finishing stations before the last one gives 500 pular. Filling the heart meter on each course gives the following:

Course 1: 500 pular
Course 2: 500 pular
Course 3: JAEGER FINAL ATTACK
Course 4: GOBBLE
Course 5: 夕焼け ～Fading Day～ (revival from Resort Anthem)
All courses: Blue Spring Express

Once a course is 100% complete (including the heart meter), nothing more can be done with it. Finishing all five of them earns a Silver Tran Medal.

Kaitsuu! Tokotoko line (開通！とことこライン) phase 2:

Five new tools have been added, obtainable at any time. Those requiring three songs must have all three songs done on the same credit.
Play the current Weekly Ranking song (this tool goes away each week, and has to be redone).
Play 3 songs from the My Favorite folder.
Play 3 songs with a base BPM of 250 or higher (surprising how few of these there seem to be).
Play a Season Line song (this is probably inaccessible to us unless possibly one of them pops up as an unlock somewhere).
Play 3 songs with Hell Charge Notes.

For those who have finished phase 1, more improvements are to be made on the existing courses. Finishing each facility earns 500 pular (including the final one), and some of them take quite some time to build (I'm looking at you, courses 4 and 5). Building a facility increases the rank bar, when this fills, a list of 3 songs appears and one can be chosen for unlocking.

Song unlocks for rank:
Arcana
On the FM
chaos eater -IIDX edition-

Rewards for finishing courses:
Course 1: An additional 500 pular (so 1000 total will be awarded on that last facility) and a bronze medal
Course 2: Welcome and a silver medal
Course 3: Battle Train -IIDX Edition- and a silver medal
Course 4: Konzert V and a gold medal
Course 5: SWEETEST SAVAGE (it's Black Another chart from DJT CS replaced its old Another chart here) and a gold medal
Full clear: 真 地獄超特急 -HELL or HELL- and a platinum medal

PULACO tickets:

Almost every song that was an unlock on Pendual that DIDN'T unlock automatically can be purchased with pular. The catch? You need a basic e-amuse subscription to do it. This is accessed on the website under the copula menu, it will be the last option. Songs that were new to IIDX (as well as a couple CS transplants) must have each of their difficulties purchased individually. The other CS songs and most crossovers have all three difficulties purchased as a set.

SECRET EXPERT courses
The 4 event boss songs (3 from Chrono Seeker and the Qpronicle Chord one) and PENDUAL Talisman can be unlocked this way. Haven't verified just exactly how, but I suspect it's just playing the secret expert courses until each difficulty unlocks (same way it was on Pendual, essentially). That's gonna be fun =P.

The Floor Infection songs remain exclusive to that event for the time being.

Mystery Line

This appears as a folder on the final stage in standard mode only (note: if you're playing somewhere that's eligible for extra stage, it will be there instead, but that doesn't apply to Round 1). The first time it appears, the game will auto-redirect to it, after that, you'll have to manually move to it. Note that you cannot use the SP/DP switch once the folder is opened, so make sure you are in the desired mode first.

There are two modes for it once the folder is opened, MYSTERY LINE and MYSTERY EXPLORE. MYSTERY LINE will appear if the game shows EVENT TRAIN APPROACHING. A random location will be chosen from four, if you have Rainbow Tickets, you can spend some here to change the location. You will then be prompted to choose whether to explore the plains (NORMAL), a mountainous region (HYPER) or the mysterious beyond (ANOTHER). After choosing that, the song of the location will appear, and you can play any of its charts (you do not have to choose the chart corresponding to the region you picked). Pass/fail status doesn't matter here, this is essentially just a preview. Three stars will be shown near the song name, these will be significant later.

If there is no event train approaching, the folder will go to MYSTERY EXPLORE mode. The game will pick a list of song charts ranging from 1 to 12 (the same song can appear more than once as multiple charts, and Beginner charts are eligible to show up as well). You only have 20 seconds to pick something, so it might be a good idea to adjust your options before entering the folder. Picking a song will remove a star from the display. After you finish a song, the pie chart will fill based on your clear type and the difficulty of the song in question (failing a song will result in very little of the chart being filled). If you completely fill the pie chart by the time the stars run out, you will unlock the song on the chosen chart, and the train will go to a new location on the next credit. If you don't fill the chart, the train will move to a new location anyway.

Normally, there are only four locations available. However, there are also some secret locations. If you fulfill certain conditions when the train is changing locations, it will be redirected to a secret location instead. The current list is as follows:

Tori-no-kimochi: Play two songs from the EMPRESS folder (this song comes from the PS2 version).
NO LIMIT: Play two OTHER songs by SUPER STAR MITSURU (NO LIMIT itself cannot be used for this).

Note: NO LIMIT's available regions correspond to regions that have already been explored for Tori-no-kimochi. If you haven't done any of the former (or have no regions unexplored on the latter that you explored on the former), it won't appear.
Note: There are two SUPER STAR MITSURU songs in the EMPRESS folder (ALL MY TURN and THANK YOU FOR PLAYING). If these are your two songs and there are still unexplored regions on Tori-no-kimochi, you'll head there.

Note: There are more locations being added later today, from a Konami post on the copula site.