This is what I have heard, don't take my word on it it's just some hearsay and I have no extended knowledge about this.
BUT, to make the aircraft realistic when taxiing on the ground the designers had to make a tradeoff.
See a normal jet can taxi at idle throttles, but the FS physics engine cannot tell the difference between ground and air physics so they had to do like this =/
I must say, I prefer that "creep" over having to advance throttles to ridiculous amount of N1/EPR just to get the aircraft moving...
We discuseed the spoilers in the FS2004 forum, and the spoilers primary objective is to keep the aircraft from bouncing, they spoil the lift so to say. The primary braking action comes from the wheelbrakes and reverse thrust. But are you talking about deployment in air? Well they can't be fully deployed in the air, only a couple of spoiler panels are extended, and not fully either (these are called inflight spoilers), but they do a good job in increasing the sink rate without letting the increase in speed
So I think the airfile is correct, but I don't know whoich 757 you talk about. POSKY's FDE's are generally great, in case you use them
