Payment methods

I can not find where I can set my bankaccount number for payments? And is it possible to add other payment methods or I must use only these 5 default?

You can find other payment methods in the marketplace.  If you just need to show the customer your bank info, then you can use Check/Money order and change the displayed text.  If you expect an automatic ACH transfer, then you need to find a payment method that supports your bank.