What a great find Wick!! I see many rewarding hours ahead for you while bringing this one back to life.
What is the doohickey near the carb? Governor maybe??
"the defects would be much less visible if I could get rid of the white left from waxes."
Are we talking wax residue that wasn't buffed properly or dull paint?
"what is good to rewax without the white powder"
Any good quality carnuba wax will work - I personally like Meguiar's...
If you have a Rural King close by, there Group-1 battery sells for $39.99 made by Exide.
https://www.ruralking.com/battery-6v-625-cca.html
It's going to be hard to beat that price or value.
I have a moto-meter that works (tested it), and it indicates that my engine is not overheating.
I had the same problem with my shiny-new Moto-Meter. Added a thicker O-ring to supplement the gasket and windshield remains clean now.
For your stripped screw problem - Drill the head of the screw off.
Any kind of antifreeze in the crankcase is harmful as it will erode any type of bearing material.
For polling purposes, I like the old fashioned ethylene glycol mixed with distilled water.
Heat Is Not Your Friend
I would be reluctant to use heat as it is very flammable with a flash point of 30°F. It also has a working temperature of over 400°F.
I'm with CW - Use channel lock pliers.