Backend error, payment options, how to limit # of listings

# 1) when trying to configure Settings > Payments tab I get a lot of errors then the input boxes below are empty. Please see attached image.

#2) Is it possible to have "free" and "paid" options available at the same time for users to register? it seems to me that it's either "free" or "paid". I hope I'm wrong, please advise.

#3) One of my pre-sale questions about Directory plugin was "is there a way to limit the number of listings a user is able to post"? I was told "Yes"... where do I configure such # of listings limit?

I'm new with this plugin and I need your guidance.
Thanks a lot, and sorry for my questions.