Need help with mounting pumps (with pics)

[rioja]

Hi guys!
I'm preparing my first watercool build and have decided to mount pumps this way:

from outside



from inside



This will took 2 bottom bays, and in third bay above pumps will be a 1Tb harddisk.
In front will be a low RPM fun, blowing to pumps and hard disk.

Kinda this way



As u may see, fan blows mostly to tops of the pumps, and a little to the basements of pumps.
So my question is do i need any clearance between case and pumps (use some supports to rise pumps from the case), or i may mount them directly to the case?
And also do i need use rubber pad (i have it already)?
Thx!