Hello and welcome - and congrats on your AR MK2, I enjoy mine a lot and still learning it after over a year 
There are already some threads that cover some of these topics in the board (e.g. Search results for 'Analog Rytm compressor' - Elektronauts), so it’s definitely worth reviewing some of those.
For 3) this might be a start: Rytm high noise floor defect ( compressor? )
For 2) this gathers some existing advice: Compressor settings? - #5 by PeterHanes