Questions About the heatsink add-ons

I’m looking for the best fan choice for Thermalright Ultra-120 Extreme

Which is better 1 fan in the middle or 2 at sides?

And since I think 2 at sides is the best choice
Is there a 120mm fan (couple of course) with that motherboard sensor wire? (red+black for electricity/yellow for the sensor) so I can see their speed in the computer and control it

does it work this way or this should be done through that part called fan controller?
If it’s the fan controller way, is it related to the heatsink or the fan? I mean should I look for a fan controller for the Thermalright Ultra-120 Extreme or a fan controller for the fan type?

Does this means that I can use a tooth paste as a Thermal grease (thermal compound) and it should do just fine?

Btw, if I had a case with like 4×120mm fans on the side panel, could they effect/disturb the heatsink fans air flow tunnel or something? I guess they should improve the cooling process but maybe there is some physical crap going here!

You can fit a fan in the middle of the Thermalright Ultra-120 Extreme? Either you're thinking of a different heat sink or Newegg didn't ship the correct one to me...

so it’s either putting one fan at the side or 2 at both sides
can anyone tell me about that sensor & controller part please?

If I remember correctly in a review I read (I think it was AnandTech) they said the difference between two fans and one was just 1 or 2 degrees so it wasn't worth it.

As for the sensor, I think any decent fan has one of those motherboard connectors so you can attach it directly to your board and control speed through software like SpeedFan.

If you get a good fan though you won't need to, just get one with a low noise rating and great speed. I have the 1600 s-flex, it's the one AnandTech used.