You have some nice bikes there, Dan
-Both plug gaps are .020.
-To change the belt on the Grande, take off the left side cover.
You don't need tools, just strong hands. Carefully squeeze the two halves of the rear pulley apart to have the belt creep to the middle of the pulley. Then you just slip it off the front pulley and work it off the back. Reinstallation is the reverse.
Set the belt on the rear pulley and squeeze them apart ot have the belt drop in, then loop it around the front. Next time you pedal it, the belt will adjust itself automatically. Just be aware that you can pinch your fingers if you are not careful.
-Cable lubing: Back off the adjusters so you have the most free-play. I unhook the cable from the lever, then put in one drop of oil for each inch of cable length. Work the cable in and out as you oil it. Do it one drop at a time. Reinstall the cable and adjust the brakes.
Do the same with the throttle and decompressor cable.
-The transmission oil is at the rear hub. look for a bolt or screw head below the black button that disengages the motor so you can pedal like a bike.
90 wt gear oil up to the level of the plug. I use a plastic turkey baster and some aquarium tubing to fill mine. Don't lay the bike on its side to fill!!! You will get oil on the brakes and spill battery fluid if it has a battery
-If the Ciao is a single speed, it will have a plain pulley on the rear hub for the belt. A variable speed will look just like the Grande.
Your fuel/oil ratio is correct. The fuel tank holds 3.5 quarts max.