Are there any sources/info where owning a shop is confirmed? Or any source/info that leads to speculation of this?
There is no confirmation of owning a shop. There has been tons of speculation on the subject, but no confirmation. Do a quick search. I think a topic about this went through here not so long ago.
I would be cool to be a thief at night, to put all that loot on the shelves in you own shop. Haha, I could just imagin an npc go like:"Well this item looks like the one I lost the other day!"
If we could own shops, that would be quite funny and I would do the exact same thing. Forget buying supplies. Just steal them and stock.