Accept credit and debit card payments at accounts desks, self check-out stations, and through the public web interface.
No. Koha does not offer any mechanisms for accepting payment.
Payments should be visible in the patron account immediately
Yes, if the payment is manually processed by the librarian and entered into Koha.
and related blocks should be removed immediately.
I think it depends. If your system is configured to block users with over X amount in fines, then yes. If your patron has been restricted based on a fine limit + a cron job, then no, the patron must be manually unblocked.
Also, do you know if you can apply a credit to a patron account if they've been accessed a fine for a lost item and then it is returned?
I think this happens automatically, but I would get a second opinion. -- Owen -- Web Developer Athens County Public Libraries http://www.myacpl.org