Marie, his little squeaks he's making sound normal. If he's having occasional dry flakes and scratching at his neck he may just have sensitive skin. Maybe it's something worse, but maybe not :) Is it cold in your house at night? Once when the power was out on my street in winter my Faye had...
You can never really know until you put them together. Two perfectly sweet rabbits might despise one other at first sight and try to maul each other immediately.
Bonding a fixed & not-fixed pair together is possible, it's just more unlikely and harder compared to if both were fixed. I'd make...
To be honest, the only thing that sounds like it would be troublesome is the poor litter habits. Not being a big chewer and getting in his water bowl are more of personality quirks than big problems I think.
You can try a water bottle as others have suggested or you can get a water crock that...
I'd ask the shelter about who to break up within the six :nod I'd worry there might be two that are especially close within the group, and of course you don't want to break them up or leave them behind to be broken up, since a lot of people probably don't go in to the shelter looking for more...