bumped into this website. unfortunately it requires a $30 yearly membership fee to get access to the meaty stuff, but browse around the freebies to see if it's worth your while.
www.chuckhawks.com/index2.guns.htm
it was also recommended to me to look into buying the book Cartridges of the World and that the yearly issue of Gun Digest is good to buy (currently available for $21 pre-order at
www.chapters.ca).
as for cleaning and maintenance, it's my understanding that each firearm comes with a manual that tells you what you need to know...tho getting an 'idea' of what goes on would be useful, if there was a nice all-in-one manual!