So what is the maximum rating of mosfets that should be used??? Irfz44n would be sufficient

 

Ok, let's try it a different way.
THIS lecture is a bit more specific.

It states you need to consider three things:
Size of the MOSFET - probably not relevant in your situation
Power dissapation - take your system, multiply max Volts x max Current and choose a MOSFET that is above that level
Id - Make sure the MOSFET has an Id greater than your current requirements.

The Id for the 44n is 49 amps at 10 volts.
Its power dissapation is 94 watts.

If this is above your system requirements, then it should work.

 

How much capacitance should be used on the power rail of the controller?

 

HERE is a nice page that should give you all you need.