To answer your last question, I prefer fresh liver over old liver (for bait, that is). For my personal eating, I don't prefer either.
As far as best ways to catch the catfish, it depends upon how big they are. I'm guessing the catfish to which you're referring are channel catfish??
If they're under 5 lbs, a cane pole could work (at least I've caught them that way). For the bigger fish...not so well.
To get an idea on how to catch bigger CCs, see this thread:
http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=114737#Post114737 and the link to Catmandoo's thread within the thread above. Good luck!