There are going to be people on here with a lot more knowledge than me. But my advice would be not to buy loads of one type first off- get a few different types to try.
Two parters would probably be your best place to start (a fitted nappy covered with a waterproof wrap) with snaps.
You don't wash at every change you put them them in your bucket or wet bag at home and your smaller wet bag when you are out and about.
I use fleece liners - when they have been pooped on I hold them over the loo and shower them down so I don't get any poop in my washer. You can use the disposable liners instead though.
Look to see if you have a local nappy library - you will be able to borrow things to try.
Also snuggleblanks specialise in bigger nappies ( they go up to adult size) so maybe have a chat with them.
Hope this has helped and not left you more confused.