No, it is not for new members only.
Existing members can received the F&F 15% off discount if they purchase 120 or more points at SSR.
Non-members must purchase at least 150 points and have a referral to receive the discount.
The discount amount can be applied towards the downpayment, if you are financings; however, they still require 10% to be paid out-of-pocket.
I believe the current UY they are selling for new members is August, so you would get the Aug 2005 allocation and then receive your next allotment this August too. Of course, with current members, you will get the same UY as the contract you are adding on to.
Important note: the F&F promo ends February 1st.
HTH