Should I got with just a boost gauge or a boost/vaccumm gauge? What's the difference ?

 

I'm assuming you are going with forced induction. I would recommend a vac/boost gauge.

The differnce is just in monitoring. A gauge with vac is not necessary but I like knowing when I'm pushing air (boost) vs air being pulled (vac).

 

Since this is a similar question and don't want to start a new topic. Should I go with Mechanical or Electrical? Pros/Cons?

 

I prefer electrical since you don't need to have the boost lines run inside the passenger compartment.

 

I prefer mechanical, they are considerably more accurate and routing a small boost line into the car is easy. I installed mine on my Super Duty Diesel and have been very satisfied with it. The installation is easier than kitchen plumbing.