PWM is really not needed for watercooling pumps - good pumps are already very quiet and there's no real reason to have them fluctuate impeller RPM every second for absolutely no gain in cooling performance.
For quiet and good performance, go with D5 or DDC pumps by Laing. They are often rebranded by Swiftech, AquaComputer, Koolance and others, but if they look the same, they essentially are the same.
Reservoirs are reservoirs - they hold excess liquid, but many like tube reservoirs for their aesthetic properties. Some like bay res's...some build their own. I've done them all; currently I use a DDC in a single 5 1/4" bay res. Works well in small cases.
When you say a pump housing...do you mean a pump top?