3.b5..........
Queen's gambit accepted; winning back the pawn.

3..Be6 is not a very good move for black. There are many other choices which present a lot more complications. The two center pawns that white gets in this opening will chase that bishop around.
3..Nf6 and 3..Nc6 are a lot more common. 3..e5 presents some unusual challenges.
The more you learn, the likely you will be to say that you have solved the problem of the opening. Yes, you have it solved if black plays badly.

3..Be6 is not a very good move for black. There are many other choices which present a lot more complications. The two center pawns that white gets in this opening will chase that bishop around.
3..Nf6 and 3..Nc6 are a lot more common. 3..e5 presents some unusual challenges.
The more you learn, the likely you will be to say that you have solved the problem of the opening. Yes, you have it solved if black plays badly.
Nf6 is useless- 4..Nf3 bg4 5...be3
Nc6 is useless-4...Nf3
e5- not more than a queen exchange.

Queens Gambit (QG) is not a real gambit.
Hence, winning back the pawn is a non-issue.
However, I harshly advice against playing QG for said reason.

Well in my opinion Black could never get comfortable position if he tries to protect the 2.dxc4...
If he just leave the pawn and focus on developing pieces that may pay off in long term.
Here is my game with interesting pieces winning idea in QGA if black plays b5...
http://www.chess.com/livechess/game?id=937987889

experience with piece activity. Yes black does have compensations. 2600+ rated players play this line as black quite willingly, and even win quite a lot with it.
I don't quite understand, probably, because I am a bit inexperience. But black will be 4 points behind, and that is very much!

It helps to be sleightly insane, to play that line.
well i dont know...its been played by 2600+ and according to my database scores quite well for black.
A link to a recorded game between two "2600+" players would help your case.

Can't quote diagrams but in you're first line. 1.D4 d5 2.c4 dxc4 3. e4 b5 4. a4c6 5.axb5cxb5 6Qf3 wins

[1.D4 d5 2.c4 dxc4 3. e4 b5 4. a4c6 5.axb5cxb5 6Qf3 wins]
first of all irontiger i cant give links to chessbase. but heres something i found online...guy named namling guliyev apparently likes this line and managed to score 3 wins and 1 draw out of 4 games. Amazingly good record eh? hes 2500+ http://www.365chess.com/search_result.php?search=1&m=6&n=5520&ms=d4.d5.c4.dxc4.e4.b5&bid=204419
also its been played 3 times by nakamura against 2600+. All draws. Not bad for black. http://www.365chess.com/search_result.php?search=1&m=6&n=5520&ms=d4.d5.c4.dxc4.e4.b5&bid=8099
Second of all soupram....please pay attention. 3. e3 has nothing to do with 3 e4.
I am not talking about this line, but about the one you put in #8.

People holding onto that QG pawn must be bugging the 1.d4'ers lately haha, 2 threads about this recently.

"I am not talking about this line, but about the one you put in #8"
same line. check the games. pay attention.
also its been played 3 times by nakamura against 2600+. All draws. Not bad for black. http://www.365chess.com/search_result.php?search=1&m=6&n=5520&ms=d4.d5.c4.dxc4.e4.b5&bid=8099(...)
In none of the games you quoted does Black let his a8 rook be taken "for activity".
EDIT: wrong, it is the case in one of those games (out of seven). Wojtaszez - Nakamura, World Blitz 2014, draw.
You will need more than one blitz game to convince me of its soundness.

You don't EVER want to have the pawn back (unless black says "Take it! I won't have the inititave after that!" and is true!) because you will have
-Active pieces (dynamic +)
-Middlegame inititave (dynamic +)
-A pawn down (static -)
- Better squares to put peices on due to more space (static +)
- No holes in your position if not rushed or panicked, but same can happen to opponent (static =)
This is why you almost NEVER want to play the QGA as black unless the opponent is unfamliar as white OR you yourself have studied a sure defense (i.e. giving back the pawn for an equal or better position)
Although I myself am not a very experienced player, which is evident with my age (13), I would like to highlight my experience on the "Queen's Gambit Accepted" problems for white.
Almost all games i play are queen pawn openings (with white, of course!).
The basic problems with beginners to this opening is how to win back the c-pawn. This problem is reviewed, analysed, and solved in this forum.
This is how you win back the pawn. Please comment.