Electric Choke

Yes the ballast is the white block usually mounted on the firewall. Some wiper motors have a similar one mounted very close or onto the motor so don't confuse the two. If you need to do some voltage checking with the key "on" then unplug either wire off the ballast........this will kill power to the coil and won't burn up the points

Something like the carb mtg studs are a good ground. The engine block is as good a ground as the battery. After all it carries cranking current, and you are only talking about a few amps