Yep, definitely DO NOT volunteer to do all care! It sounds heartless and awful, but if you do you'll get very little help at all and you WILL need it.
Washing - strip wash with a bowl of water and a cloth. You can also buy wet wipes designed for bed baths on Amazon, they are much much more effective than baby wipes or toilet wipes, and you can heat them up if you like in a bowl of hot water (don't open the pack, just drop the whole pack in hot water), or some are designed to be microwaved to heat.
You can also get no-water foam that you rub on with hands, rub off with a towel (you mustn't let it dry so do small patches rather than big areas) - I found this stuff surprisingly good!
Ask for help from DN and OT, they are out there but you'll really need to ask and insist you need help.
Bed-wise, a medium firm pocket sprung mattress should be fine, you may want a slide sheet to help him roll over, but hold off on memory foam until he's home and tried stuff out - whilst it is supportive, it also may make him sink into the bed too far and then find it much harder to move himself!
If he does need more support, OT/DN can sort out a ROHO mattress cushion which sits on top of the mattress under the sheet - it's inflateable and very supportive (I have a ROHO cushion on my wheelchair and sit on a single mattress section on my sofa!)
Lots of equipment can be hired rather than bought too, if you feel you need something but OT/DN can't supply it.
And don't be surprised when random items get delivered by couriers - thats pretty normal, and then some weeks later someone might show up to fit it or explain its use! You get used to this!