The loan limit and the stake will depend on the credit score of the borrower. That's pretty simple: the loan limit will be as high and required stake from KYC and Auditor masternodes low as the credit score be good. All loaners indicate what credit score they work with. The higher score you have the more potential loaners you get.
It turns out a kind of auction?
Yes, sort of.
If you have a score X, loan will be issued from those holders, who want to borrow with such score, group with lowest interest will be chosed among them