You should be able to just define which frames you want to render :-) Also you can even render out frames as a set of bitmaps, which means that even if your bryce crashes midway an animation render, you havent lost the frames it was already done with. Unlike some compressed animation formats which can get corrupted when bryce crashes before its done (its happened to me)
I think its somewhere in the animation setup or document setup or such... dont have bryce here so i cant check exactly but the setting should be there.

As for taking your last frame. Just select every object that gets animated, go to the last frame, and give them a key. Then go ahead deleting all animation keys before that frame, and eventually when the keys in ur last frame are the last keys left in ur scene, all your frames will have the position of your last frame. When you've achieved this you can delete the last keyframes which should still leave ur scene in tact. It's not a pretty work-flow by any means but i dont think bryce has an actual feature for doing this kind of stuff automatically.

(_/)
(='.'=)
(")(")This is Bunny. Copy and paste bunny into your signature to help him gain world domination.