RAM - Double Sided / Dual Channel & Frequency Limits

First off I wouldn't worry about double or single side ram. You can read for days on the net all kinds of opinions on this subject. Their are ram sticks that are not physically made for a motherboard and they use a notch location to try and stop people from installing on the wrong board. Get the ram that is qualified for your motherboard and cpu. Can you go to a faster ram other than what is qualified for your system. Sure you can. From 1800 to 2130 I don't believe you will notice the difference. I'm running faster ram than my intel cpu call for. Intel specs are 800/1066 and I have 2000 O/C. I can't get it over 1600 because of the memory controller in the cpu. If I had to do it over I would not buy the 2000 O/C ram.
It would be nice if you could complete you ((My System Specs)). It will follow your every post. Look in the lower left corner of this post and tick on it.

For the first question dual sided is dual channel memory or commonly referred to as "Dual in Memory Module" dimm. The old single sided memory was called simms. All memory now besides something like an SD card would be dual channel.

On the second question regarding memory speed if you install the type the board supports in case the board only accepts standard ram and you install performance memory as seen mostly with old boards the memory will simply run at the slower speed unless the memory clock is raised up to the max. Even then however you most likely only see the fastest speed supported.

If you should happen to install 1.9v memory on a board that takes 1.5v dimms the fastest memory speed supported will be backclocked down two speeds as it was found here when ordering the OCZ Gold 1.9v DDR3 1600 to end up with 1066 until raising the memory clock up to get only 1333.

On the new 7 Pro case the same 1600 memory went on a board that supports 1.5v 1333 memory and still sees 1600mhz when the clock was brought up to the max being only one speed faster memory used. You might see about 1800 or 1866mhz for the 2133 memory there however at best.