in order asked
heat-sinks are decorative for the VAST majority of RAM.
Decorative, you'll be fine with naked RAM sticks
If you get a pair of RAM make sure you get a matched pair. matched pairs are tested to work together as one unit. Dual channel Memory. Mixing RAM modules can be tricky at best. I suggest a matched pair, paying for a matched pair of RAM for Dual Channel Ram is a good thing, paying extra for decorative fashion is bad. IMHO. Dual channel Memory is a nice boost in performance.
The faster RAM will go at the available bus speed. the RAM should slow down to the 2133mhz.
The QVL is a good resource but it is not a list of the only RAM that will work. the QVL is simply a list of pre-tested units.