You are allowed one transfer in or out each UY. This is designed to prevent two owners from swapping their home resort advantage: if I transfer my points to that person, they couldn't transfer theirs to me - each party would have used their transfer for the year with the first transaction.
The receiving member can bank but not borrow points. This is designed to prevent going around the above rule by transferring in both this and next UY and then borrowing into this one. Receiving member can bank points if inside the banking window.
Because you can only do one transfer a year, if you are renting points, its to your advantage to transfer as large a number of points as possible. I believe I saw you are currently active on the rent/trade board. I would enforce a high limit: 100-200 point minimum or all your avail points. I would also charge a dollar or two premium on a transfer. It's easier on the buyer to accept a transfer but that comes at an additional cost to you: you burn your transfer for the year. Besides, there is a higher demand than availability for transfers. I wouldn't sell for less than $13 a point - more if you're willing to transfer less than 100 points. I can get a transfer from a broker for $15/point, but they are normally 200+ Point deals. If you're willing to do less points, then $15/point isn't unreasonable and a better deal than someone can get elsewhere. I'd hold the line at 16/point If you have a high demand resort inside its home resort advantage.
Transferring members cannot transfer borrowed points.
Points keep their home resort and UY. In most cases, they don't show on members account and member will have to call MS to use them. I understand that they will show in members account if they are the same resort and UY as receiving member.
Rules say you cannot sell transfers. This is widely not enforced and the reason behind the rule appears to be to absolve MS from having to deal with disputes involved in such a deal. If it's not allowed, then you can't complain if the process goes awry.
All transfers are final. As a result, if you are doing the transfer, get paid first. I personally wouldn't even do 50% now and 50% later.
MS will give transferring member a confirmation number to give to receiving member. The receiving member will have to call to confirm the points are in their account because they won't show online. You'll need their member number and prob address. I don't think I'd do a three-way call because that would give the other member access to your confirmation info (your last four, etc.).