1A, My rather wide and square glasses fit with about half an inch of clearance under the sun visor on my Gmax flip-up. Size large barely fits in the frunk.
2, I am definitely in the pro center-stand camp. Maintenance and loading cargo are both made much easier.
3. I believe the main advantages to a lithium battery are better cold start performance, and weight savings. It's rather temperate in SA, correct? The weight savings probably wouldn't be noticeable. On a lightweight dirt bike, yes. Big downside of lithium is cost, and they're just as easy to kill as lead acid if you leave your lights on a couple times.