Hi Muris,
Thanks for reaching out to us! Great questions, let me help you with them.
To your first question the answer is yes! You will find further details on how you can do that in this article about Abstract Post Types.
To your second question about the payment, no, at the moment that is not possible. Although there is something in the works (the furnaces are hot. Super hot!) I cannot give you any fixed launch date.
Until that happens you will need to use one of the eCommerce solutions you listed.
Let me know if you have any further questions.
Cheers,
Andras