I have rented several times and people all seem to do things differently.

Some people want all the money at the time they make the reservation. Some people take half down when they make the reservation and then half by the date they would have to cancel the reservation if the points were unable to be used (I believe that's 30 days....a member would know better than I). And when renting a rather large number, some people have been willing to take multiple payments leading up to the reservation. Regardless, there is a matter of trust involved.
As far as amount per point, I have personally rented anywhere between $8.00 and $10.00 a point. The general going rate these days unless someone is trying to get rid of points on a use year that is running out seems to be $10.00 a point, although I have seen some people ask for as much as $12.00 a point.
I don't know what other questions you might ask and maybe someone who has rented TO someone here before might have more thoughts for you but my experience has been that it varies.

I think you can make up your own guidelines.