I've looked at them a couple of times and gave up. What they do is contact the hotel and reserve the room - it takes time and is not a true instant online booking. You pay a deposit when they come back to you with an offer and then in full, in advance later . PR will then issue a voucher that the hotel should honour (not inclusive of charges like room service,parking etc.)
Both times I tried PR they came back after 24 hrs or so and said not avaialable - I found it easier to restrict myself only to hotels/agents with instant online availabilty/reservation systems or directly where the hotel I know will answer quickly (Majestic Suites or Dynasty in BKK) - tell them the price PR are offering and they might match it.
Otherwise your questions are answered in PR's FAQs:
http://www.precisionreservations.com...abase/FAQ.aspx
Cheers,
K.