Does it really matter if I buy the game from Steam or Origin? It seems all of the DLC is bought from Bioware's website using some fake money that is the equivalent of Microsoft points. Is that correct?
You can redeem your Steam key on Origin if you want, so no, it doesn't matter. And yes, they want you to buy the DLC with Bioware points. If you use the Steam version, you'll download an .exe which will add the DLC. If you use Origin, it's integrated into the client, but they still make you pay in Bioware points for some reason.