Viper,
These are the clears I've used. Mostly the CC635 for airplanes and heli canopies and lately the CC639 (Super clear but a few $$ more). I've had great success laying these clears over the Pactra RC car paint (airbrushed or spray can) as a time and cost saver. I use the SW base coats for the larger projects.

CC635 ULTRA 7000® HS Air Dry Clearcoat
CC637 ULTRA 7000® Maximum Performance Clearcoat
CC639 ULTRA 7000® Super Glamour Clearcoat

Pick you hardener based on your painting environment:

UH22 Ultra System Rapid Hardener
UH33 Ultra System Medium Hardener
UH44 Ultra System Medium-Slow Hardener
UH55 Ultra System Slow Hardener
UH60 ULTRA System Air Dry Hardener

These are self-explanatory and have the temp range on the label:

US1 ULTRASOLV® #1 Cold Temp Reducer
US2 ULTRASOLV® #2 Cool Temp Reducer
US3 ULTRASOLV® #3 Moderate Temp Reducer
US4 ULTRASOLV® #4 Warm Temp Reducer
US5 ULTRASOLV® #5 Hot Temp Reducer
US6 ULTRASOLV® #6 Tropical/Desert Temp Reducer

You can thin out the last coat of clear as much as you like (I've gone over 200%) with no adverse effects in 60-90+ deg temps.

WRT the spot putty, I believe the blue, red, or green will work fine and the auto paint store should carry either one. I use both the green and lately the red spot putty on my current street rod project.

Good Luck!