My advice is leave the 32-bit floating-point default. The conversion from 16 or 24-bit to 32-bit float, and back is lossless. The ONLY “downside” is the TEMPORARY need for more disc space. Virtually all audio editors & DAWs use 32 or 64-bit floating point “internally”. Don’t try to out-smart the smart people! If you are not doing any “processing” you don’t need floating point but there’s also no need to mess with the defaults.
If you don’t want the data altered at all turn OFF [u]dither[/u]. As a practical matter, it won’t matter either way… You can’t normally hear dither (which is very-low level noise) or the effects of dither at 16-bits or better, and because vinyl is “self dithered” from the vinyl noise.
Levels will be set so no normalization etc. will not be necessary.
Digital volume adjustment is also HARMLESS. It very difficult to get the “perfect level” while recording without clipping and you might have to record twice (or 3 times). The standard practice is to shoot-for -3 to -6dB, leaving plenty of headroom. You don’t really need headroom… Nothing bad happens when you get close to 0dB but you’ll get clipping if you “try” to go over and analog levels are always unpredictable. (Pros typically record at -12 to -18dB.)
If you are old enough to remember analog tape, you wanted a hot signal to overcome tape noise, and tape tends to soft-clip so it was OK to go occasionally “into the red”. With digital there is no tape noise and it will hard-clip if you “try” to go over 0dB.
I generally normalize the album as a whole, keeping loud songs (relatively) loud and quiet songs (relatively) quiet.
Even if you normalize (AKA “maximize”) vinyl it’s usually quieter than a digital original and your digitized vinyl will be quieter than most of your CDs. There are two reasons for this. Modern CDs & remasters are often victims (or victors) of the Loudness War. Plus, the vinyl cutting & playback process tends to make some peaks higher and some peaks lower (without changing the sound of the dynamics). So if the digitized vinyl and digital original are both normalized for 0dB peaks, the digitized vinyl will have a lower average (or RMS) level and it will be (slightly) quieter. This increase in peak-to-average ratio (crest factor) fools some people into thinking the CD is more compressed, even when the LP & CD were made from the same master.
Maybe a couple click removals but that’s all.
Audacity has Click Removal (automatic), Repair (manual), or you can zoom-in and manually “re-draw” the waveform. [u]Wave Corrector[/u] is a FREE automatic declicker. [u]Wave Repair[/u] ($30 USD) offers several click removal methods and it only “touches” the audio where you identify a defect (which is usually very time consuming).
For hum, hiss, and low-level crackle, you can try the regular Audacity Noise Reduction effect. But, you can sometimes get artifacts so listen closely to the results and you may only want to apply it to fade-ins, fade-outs, or other quiet parts where the background noise is noticeable.