Well, as Brian knows, I won't go into scanning/faxing and AC, and I certainly won't go into File Assistant Pro, which I think one user MAY be using.
But....to answer your questions:
Fujitsu is the way to go for pure scanning.
Yes, they come with Twain drivers
You should look for at least a 50 page feeder
And....
You could scan 10 Terabytes into AC and not slow it down on millisecond. How much you scan into AC has absolutely nothing to do with its performance.
There you are, a definitive answer! You're the greatest, Bert.
Bert, I think you need to write an omnibus treatise on faxing and scanning into AC and post it on the Wiki!
I will then sneak in by night and make little changes to it!
