Verify my MOSFET selection process?

The lowest gate drive voltage the CSD18511KCS is rated for is 4.5V.

Threshold is not relevant, its nothing to do with the on state. (*)
Rds(on) is the figure you want.

You are very unlikely to find a 3.3V rated MOSFET except in a surface mount package.

What you could do is use a gate-driver chip and a 10V rated MOSFET. Gate driver chips need about 12V supply, take 3.3 or 5V logic signals in and drive a MOSFET gate.

(*) Think of a tap. As you start turning it on and it starts to drip slowly - that's the threshold.