It's a great age for soooo many questions!! ;P My DD asks alot about how things work / move - eg: a truck... a bit easier to answer but she can still stump me from time to time!

I guess my answer for the evolution question (we are non-practising Catholic) would be to answer 'some people think XYZ, others think ABC' and answer it from a non-religious and religious POV.

The two sites posted, one by epacris and the other by catherine are a great start! Have fun!