There is no real information on PD right now to give a clear answer. It could clock higher or perform better than BD but it would need to perform quite a bit better to beat the 2500K/2600K (current Intel CPUs) in performance and be priced either the same or lower than it.
Honestly I think its a waste of money to buy a CPU to wait for a new one when you could just take the extra money from said Athlon II and put it towards a GPU or better CPU now. Either get a Phenom II X6 or buy a 2500K system.
There is no release date for PD other than rumors for Q2/Q3. If its Q3, you will be waiting a while an GW2 and D3 will launch before it is out.
As for the RAM, honestly, 1866MHz RAM is a waste. 1600MHz is the best option as its cheap and will do what you need. Not sure why anyone other than someone using a Llano based system, that can benefit from the faster RAM on the IGP side, buys that RAM.
Games will not benefit from 1866MHz RAM nor really that much from even 1600MHz RAM. Only applications that utilize memory or servers benefit from faster RAM.
To answer your question, the RAM is clocked to DDR3 1333. Its just that it will show 667MHz that when in dual channel will be DDR3 1333MHz.
For example, I have 16GB of DDR3 1600MHz Corsair Vengance RAM. In CPUx, the memory screen shows it at 800MHz but its clocked at 1600MHz in dual channel.