I am sure you can. Make sure there is different name on the both account. If ebay suspend both account, e-mail them and explain to them that one belong to you and one belong to your wife.
Why use a bank account? Why not a credit card?
Here is what to do about paypal, add a second e-mail (your wife's) to it. The e-mail address used to start the paypal account can be the primary e-mail address. One of the secondary e-mail addresses could be your wife. And have your wife put that secondary e-mail address into her paypal account.
Instead of asking the questions on here, you should talk to someone on eBay about it, or read their TOS. They've got a live chat thing that you can use to ask them. As far as I know, though, there is only 1 person per account. If it's a bank joint account, you could get your wife her own CC # and a PO Box. That might help.