Welcome to AudioCircle Juggernaut!!!

I like dbpoweramp for ripping and converting. Don't know if it's available for Mac... You can rip to Apple Lossless with a free codec from them.
You can't use iTunes to control Squeezebox. But I think Squeezebox server can play tunes from iTunes database. Is there an Apple Squeezebox Server now? Apple lossless is just as good as flac and will play in an ipod. flac won't play on apple products without a software plugin or workaround.
As for flac settings, the default is 5 which is a compromise between compression speed and final file size. You can change the setting for less space or faster compression, but it doesn't affect the sound at all. I stick with 5. There are no other flac settings. But there are a lot of settings on the various rip programs. Read the help file to get to know what's going on before you rip too much with a wrong setting.
I recommend that you embed album art in the tracks. It makes them a little larger, but you always have the cover art no matter what happens. Space is cheap now.
I like to organize my library with separate folders for genre artist album, although SB and portable players don't require this. Easier to find a track manually if you need it.
Get an external drive for the music collection, or as a backup. It's nice to be able to carry your collection to friends' house.
Sorry about the crash. Should got a PC... haha j/k
Again, welcome!!
Rich