welcome to BinkyBunny!
i’m not sure if i understand your question… by "not work" do you mean can a male rabbit impregnate a female after neutering? i believe they can for about a month afterwards, so i think you’re supposed to continue to keep them separated during that time… which is a good idea anyways to let them fully heal. are you having them both altered the same day? if you are, i think that’s a pretty good idea, that way after that time you can reintroduce them both hormone-free.
now the second question… every rabbit is going to respond differently to a decrease in hormones. you may see a reduction in aggression and destructive behavior, but you may not. the hormones take, in general, about a month to dissipate, but i know with my rabbit i saw a decrease in aggression (namely annoying nipping) almost immediately. but… i believe that overall… if a bunny loves chewing carpet or wood or whatever, that’ not necessarily going to change b/c of surgery. rather than thinking a surgery will "fix" your rabbits annoying habits, you may want to find better alternatives for your rabbit, other toys and activities to take up his time, or maybe rethink your bunnyproofing so the prized possessions are not in danger from bunny teeth or nails. people tend to think that their rabbit will fit into their life, whereas actually, they need to adjust things to better fit with the rabbit.