Swapping the voltage regulator on the arduino?

that way only Mega signal lines and a ground would have to wire between them.

What do you mean?

It's basically a "motherboard", but not too large in size...

I was planning to have two of these:

http://www.mouser.com/ProductDetail/STMicroelectronics/LM323T/?qs=sGAEpiMZZMtUqDgmOWBjgHOEICDv%2FyCoO8eaZVThujo%3D

which come both in to-3 and to-22 forms... One for the servos, the other for the rest.

As an addon question, what is the category/type of the "polarity protection diode" between the power jack and the regulator? I will need to change that accordingly too.

Not to bombard with questions, but much of this is a new area to me, so one more thing: What is the diode exactly for? I get the concept, but what exactly would cause "backflow" of current on the board?