time to buy paint, how much do i need?

[lofly'a]

gotta buy paint and clear for the tahoe 2-door color change from emerald green to black, so i'll be painting the outside plus the jams, underside of hood, inner fenders, and both bumpers. as far as i can estimate, i'll need 4qarts of each base, and clear. i'm using PPG- dbu base coat, and concepts 2021 clear. is this enough or too much? also, i have some new urethane parts that i prepped as per boardmembers suggestions to get off the mold wax residue. washed w/ dawn, repeatedly!, prepped w/ wax and grease remover, repeatedly!, scuffed w/ brown scotchbrite, ....... and the water still beads up and rolls off like they have been freshly waxed. is this normal, it did this with the urethane cowl cover 1st, and finally after repeated scuffing the water finally sheets off but not the bumper cover and front grille shell. i am doing the escalade conversion so i have a lot of urethane upfront to prep and paint. any thoughts or answers??