Quadad/PapaV: Depending on which source you best believe, the model would be 0.018" short of max (full-size car is 205.8"), or 0.01 long (full-size car is 206.5"). That's like two strokes of sandpaper on the nose... I don't think anyone here would raise a fuss over that.
Old Blue: You're right. You want the body, bumpers, headlights, glass, and tails to build up the SR. Most here put in side windows too — I use the clear plastic from packaging: cut to fit then glue it in. Paint the insides of the windows with a light coat of black — it makes them look tinted and hides the guts of your car, helping the illusion of real.
Depending on how detailed you want to be will determine how involved your painting will be. I prefer primer in all cases, but you can often get away without it. If you are really going for a smooth, realistic body, you'll want to sand off any mold seams, and possibly fill in any indentations. Primer will help you see those imperfections. Use lacquer paints. Duplicolor is my fave, but the Testors and Model Master paints do a pretty good job too.
Wash the body and parts in soapy water first, to clean off any production residues that might interfere with the paint.
I look forward to seeing the build!