For the errors with they game I recommend just waiting until BIS releases a few patches for the game because BIS' games are usually a little laggy and full of bugs when they are released. (you know, the game is huge!) BIS' are good at fixing their games. :)
"Operation Flashpoint" 2 seems to be a more arcade than simulation, thats why he compared the games. ;)
You remember playing it, I am still playing it and it still is one of the best games ever!
Funny, that you say so because ArmA is Operation Flashpoint in many ways:
-ArmA & OFP1 is made by BIS.
-They both use the same game engine. (ArmA is using an improved version obviously)