Sorry you're having issues!
'X3DAudio1_7.dll is missing' is a
common generic error indicating that something might be up with your DirectX
installation (perhaps it is outdated)
Looking around at other game's forums suggests that reinstalling DirectX can help. If you google the problem there is a load of help available also (just search it in combination with popular games like Ark)
As for 64bit vs 32bit, I recommend that you find out which version of Windows 7 you use and then play the version which matches that.