You should be able to just download it and do whatever you want, but let me know if you have any issues. And yeah, I never finished filling in the Bugs section or got near completing my museum. Oh well.
Museum donations should always be top priority... unless you don't realise it hasn't been donated, I guess. Oh well, May's not too far away. I won't encourage you to time travel.
Were you talking about Wild World or New Leaf? TPC suggests New Leaf, but there is an encyclopedia in that general area in Wild World, I think. Never really used it, to be honest, and now I'm just forgetting things. Sorry if I made a mistake.