Thanks Junior JBL.
As for spray gun, I bought a DeVibiss SRI Minigun a few years ago and really like it so will be using it for this job.
I've done quiet a bit of reading so far and am ready to proceed. Lots of practive before hand.
The issue I have now is the spraying area (my 2-car garage); It's packed and very dusty from saw dust resulting of my recent project DIY audio rack that I just finished. I didn't have this many stuffs in the garage a few years ago so it was easy to cover up every with a big sheet of plastic.
So spraying is going to an easy part of this project. Preparing / making temporary paint booth is going to be a big challenge plus the temperature is dropping in the past few days so I'll have to get this done really soon. Wish I have more space.
I am planning to first get the filler work done on the damaged areas and sand the rest with 600grit dry sand paper then work on buillding the booth (with PVC pipes and cover the frame with large plastic bag). I have to get the spraying done in one day since I have no parking space for my cars on the street so have to properly plan this activity.
Question for those who have painted or repainted speaker boxes, Did you use wet or dry sand papers? With wet, I am concerned about the bottom of the speakers since they're untreated so don't want the MDF to be soaked with water. I plan to use dry sand papers for this reason.
As for the paint, I think I'll be using BC/CC Nason.
Thanks to all for your input.