I'm not really sure exactly what you want to do, but I'll give it a go.
At this point I rip CD's to FLAC with EAC. If you're on a Mac I think the best option is XLD. Both require you set up the programs to get the best results. I figured it was worth the extra time to set up EAC perfectly so I don't ever have to go through ripping 400+ CD's again.
For EAC I use this guide:
http://wiki.hydrogenaudio.org/index.php?title=EAC_Lossless_BackupSomeone else will have to chime in for an XLD setup guide.
I have no idea how to convert DAT's as I skipped over DAT. I'm sure that info is around here somewhere.
As for storage, I keep all of my data duplicated (nightly) to 2 identical hard drives. Also I keep another identical drive off site (currently these live in my safe deposit box at the bank).
Again, I'm on Windows 7 so that's all I know about. I use SyncToy from Microsoft (free) to run my nightly backups. This does require a little configuration, but it's not too hard to do.
I used this guide:
http://www.howtogeek.com/howto/25046/schedule-synctoy-to-run-automatically-with-task-scheduler-in-windows-7/In addition I have all of my favorite music stored on Google Music in MP3 form (all 320kbps MP3's). This isn't a great backup option because you can only download each file 2 times...but I figure the more places you have your data backed up the better...and obviously it's nice to be able to stream it all to my smartphone and to my work computer.