I'm trying to make a collection here, does anyone knows how many versions of soundtracks were used IN-GAME in the SFII series, including every arcade/console/computer port (From The World Warrior through HD Remix). Can anyone link me to those soundtracks? I know im asking for a lot, but could someone help me out?

That all depends if you count audio rips as "soundtracks".
If you're talking about commercial soundtrack releases, then it's four soundtracks:

1. Street Fighter II Perfect Original Version from the Street Fighter II Collection Box (PCCB-00125)
2. Super Street Fighter II: The New Challengers (SRCL-2822)
3. Sound Complete - Super Street Fighter II X N/A
4. OC ReMix: Super Street Fighter II Turbo HD Remix Official Soundtrack (OCRA-0012)

If you want to include CD-based games with easy audio rips, then there's also:

1. Super Street Fighter II (PC Game) - Contains an arranged soundtrack that I believe can only be found on this particular game.
2. Super Street Fighter II/Turbo (FM-Towns, 3DO, Playstation 2 game) - All three ports have the same arranged soundtrack, but it's unclear whether or not the FM-Towns version (Super Street Fighter II) has the Gouki/Akuma track since it was a Super Street Fighter II port. Also worth noting, the PS2 game (Hyper Street Fighter II -Anniversary Edition) has some minor audio defects on certain tracks when ripped while the 3DO game (Super Street Fighter II Turbo) is difficult to rip. I recently bought the FM-Towns version of the game, so I'm not sure if that will be a pain to rip, but from what I've read, it might be the best option out of the three.