48khz -> 44.1khz is resampling. sound forge, cool edit, adobe audition, wavelab will all do this in high quality. the uv22 apogee dithering doesn't come into play here, you use dithering to go from 24bit -> 16bit.
if you're recording to the jb3 via the ua-5, you should never use the advance setting and record at 24bit. if you do that the jb3 will truncate the signal down to 16bit, which is ok, but doesn't provide the best outcome.
whether you choose 48khz or 44.1khz is up to you, i do 44.1khz, cuz its just easier. you need it at 44.1 for splitting, seeding, and burning, and i can't (nor most people for that matter) tell the difference.