All the details on FLAC as a format are at:
http://flac.sourceforge.net
Don't quote me, but I believe the format itself can basically support any sample size and frequency that you would realistically need, now and for a long long while. The issues would be that you'd have to get into the command-line a little bit probably, and you'd have to make sure whatever you used as a player could handle what you encode at.
If I were you I would play with FLAC a bit on some of your WAVs and see what's what -- the reference implementation is, of course, freely available on the main project site.
As a general rule, I am currently of the opinion that FLAC is the ideal compression solution. It's larger than a lossy codec, of course, but I don't imagine anyone on this site would want a lossy codec if they had a choice. Hard drive space isn't cheap, but compared to what you'd spend for the rest of your audio equipment, it is. Having lived with this kind of a system for several months now, the only real complaints I've had are minor ones related to the library software itself, and those types of solutions ar getting better every day.
Go for it.