First question...I am looking at a motherboard on Newegg and in the detail section that lists memory standards it has (O.C.) listed next to some memory speeds. e.g. DDR3 2000(O.C.)/1800(O.C.)/1600(O.C.)/1333/1066
Question: Does the (O.C.) mean anything over /1333/1066 MUST be overclocked or anything over /1333/1066 CAN be overclocked? I don't want to overclock anything, does that mean I can only go as high as 1333?
Yes, without overclocking you can't run current generation processors above DDR3 1333. If the motherboard and memory support XMP and a higher frequency without overclocking (for example, DDR3 1600), though, your memory can be automatically overclocked to that frequency by the motherboard.
Second question...I am looking at 1333 memory speeds and in Newegg there are 3 different kinds (DDR3 1333 10660, 10060, and 10666.) What the hell is the difference? Are all 3 going to be compatible with a 1333 motherboard standard?
It's all the same. 10060 is just a typo.
You can compare the performance level of a sets of memory that run at the same frequency (DDR3 1333) by their CAS latencies (lower is better). For example, DDR3 1333 CL7 is better than DDR3 1333 CL9.