Questions about making hard kefir cheese

I am attempting to make hard kefir cheese in a cheese press. Unfortunately the cheese press I purchased did not come with specific instructions. I was able to find an article (http://ift.tt/1DiS4dK) but it is vague in certain respects. Therefore I have two questions about the process.

How much PSI should be outputted onto the kefir to make hard cheese?

By the time the milk has been turned into kefir, it has already been sitting out for perhaps 24-48 hours. Is it necessary to refrigerate the kefir while draining it and while pressing it into cheese, or can it sit at room temperature during this process?