Prewashing help for a newbie

Hi,
I'm new to cloth nappies, have just 2 BG AIO I got off here pre-loved.
So, I've just ordered 2 innerds and a wrap from the Wizard Duo (motherease). When I get them I'll pre-wash obvs, do I need to do this with them alone in the machine? Or can I put dirty BG in too?

(Also have upstairs my first poopy cloth nappy.. putting off dealing with it... lol) Can I put it straight in machine, pre-wash and then wash? It's a bit mushy toddler poop (sorry if tmi). Do I need to shower off the worst of the poop first? (into bucket.. just read about this)

Thanks =)

Also, do I need to prewash the wrap??

yes they need a prewash - I never prewash lol

poo I scrap flck rinse off the worse then I always do a cold water rinse in the machine before washing them x