Analogue-sequencer

p3 experts: if i wanted to set up my p3 as a realtime midi looper, 
where track one would be a short 8 step sequence track 2, 16 step, 
track 3, 32 step up to 64 step, whats the quickest way to set that up? 
also is there a quick way to set up a multi bar preference for say 
having a track's auxes be aux note; for polyphony?

part 2 of the question, or actually a whole other question.. when im 
recording realtime and i cycle through a section i messed up and i want 
to erase, it seems the erasing doesnt actually happen right away, is 
there a setting for that?