Can I go with Corsair for the 2. stick?-----yes
Does it have to be 3200 RTL ?
If the 2700 is cheaper, can I go with it?------thats a little murkier question----my gut tells me you would be ok---obviously you would be limited to running BOTH sticks at 2700.
Also, somewhere in this forum I read that this kind of memory tends to be hot and that there is a cooler available.------they are called "heat spreaders", and you can probably get em anywhere..look at
www.newegg.com
JP
http://www.newegg.com/app/listProduc...tby=11&order=0 some stuff here...mixed types