Becky,,
I don't believe hospital beds come in any other size but twin X Long. Its just a few inches longer than a twin. When you combine it with another twin X Long it becomes an Eastern King or just a King sized bed. I gather from what I read, you will be sleeping in the room alone because of size.
The important feature you need to make sure your bed has, is the whole bed raises and lowers. I don't mean the head and foot but the whole bed. This way your husband can raise it up and not have to bend down as much. Raise it when lifting, changing nappy, changing sheets, bathing you et cetera. Then lower to put you back in bed. Your caregivers back will thank you for choosing this feature.
As for the mattress, I told somebody who posted this same question, that I'm taking the princess and the pea approach. I get 1 try it and then move to the next one. I just want to be 110 percent sure before I settle. Insurances only cover 1 bed in 5 year time periold, so try before you decide. One D M E told me to get the gel filled topper. That's my next choice.
Good luck and happy sleeping!