What should i be getting ?

[Oreo]

The RAM stuff is confusing.

 

[Nagasama]

Think of it as a picture in your head and its alot more simple.

Also, about o/c, does having looser RAM timings allow you to o/c ure cpu more? So basically, do you need to underclock your RAM?

depends on how good your ram is at overclocking, and how much you overclock your cpu.
but basically, yes...if you are going for a good overclock, you will need to underclock your ram to keep it near its rated speed.