That is a lot of question in one post. With a lot of the answers depending on who reponse

I have done this to two Top Flite Gaint P51's.

I strip it off before building, it makes fiberglassing the elevators stabs etc a lot easyer.

I use 1/2oz fiberglass matt, I think I orderd 5 yards off of ebay very cheap. You want to buy it this way, you will pay more for the hobby store fiberglass and may not cover your wings with out a seam.

I use Z Poxy Finishing epoxy from Tower, great stuff, Some peaple will thin it even more with Alcohal, or MEK from Lows. I use MEK just a tad.

Once you strip off the covering check for damge, use light spackel for dry way to fix any dips, damge, or blending before covering in glass.

Wach some vids on youtube.

To glass the wing do the bottom first, stop at the front and leading edge, once dry, and the edge and do the top with a little over lap, once dry sand.

Lay the glass on the modle, mix your epoxy, use cheap brush from lowes, I like 3in for big projects, once the whole thing is wet with epoxy, take some Tolet Paper with out any patterns on it and roll it over the wing to soke up any exsess epoxy. Should only need one coat of epoxy, but if your mat is showing to much do it one more time once dry with a lite sand inbetween.

Open areas of the wing are a big pain, you have to eather add balsa and sand to perfect shap,

option 2 is (exsample I had to do this on the rudders of my P51) I use very thin "Flight Skin" its a very thin fiberglass sheet, Just use CA to secure it and it great for open areas, you may have to skill use some regular fiberlass were the flight skin dont bend.

I make one Rookie mistake my first time, did all this then put the primer on, to try to help it dry faster I put it out side.. Bad, it made the epoxy cure faster and it made some ripping show up in my wing that were not there before putting it out side.

When it come to paint that is a whole huge ball of wax, peaple use everthing from Krilon 2x (my fav spray can) to PPG Car paint.

So depending on your plane will help you pick a pain, Ie nitro fuel save, electics ets.

Its a lot of fun, Oh and buy a really good sharp pair of hair cutting sisors for the glass mat...
Mike