Free sag is how much the rear end sags without rider on board. Pull up on the bike while vertical to top out the suspension and see how much it sags when you let go. Too much and it'll sag when resting on the sidestand. The shocks should be fully topped out on the sidestand if the preload is set correctly so it won't be any different than lifting the rear. Watch some Dave Moss videos if you haven't already. He recommends 5 to 10mm free sag.

You basically set the belt tension with zero suspension sag. If you had way too much free sag for some reason, you might not be able to adjust the belt on the sidestand and would have to use a lift to get the swingarm to go all the way down.

I would use the recommended setting because it has to be set so it'll never go too loose. I've heard of teeth being stripped off a Zero FX belt from being too loose but never a problem with the factory (overtightened) settings. One FX owner insisted the dealership made the belt too tight so he loosened it. The belt lost teeth and the shop put another on. Again, he thought it too tight and again, he loosened it. Dealership installed another belt and the owner finally left it alone.

Yes, or for us Americans, about the thickness of a cigarette. You're only likely to have problems under certain conditions if looser. Low gear, high HP, good traction, irregular road surface, supension topped out all contribute. For high speed and mileage with only soft take offs, you can run a little loose but the Bolt isn't meant to be ridden that way . Some bikes can run up to 2" but probably use a different swingarm angle and a thick, old style belt.

I have the Progressive shocks that make the bike lean a lot more on the sidestand than the stock C-Spec so I know the swingarm arc is causing the belt to get tighter than Yamaha orginally intended. I set it to stock specs and now it's almost at 1/2". I won't make it any less if it doesn't increase much more soon or cause a problem.

My MP tension gauge seems to be assembled wrong with the o-ring installed inside so the spring can't do it's job. I lubed it with silicone to make it move freely but I'd like to rebuild it. Thought I'd mention that in case others got one that felt like it sticks.

I couldn't find a video of how slack a belt gets under load but here's a chain:

https://m.youtube.com/watch?v=-t3QLWMse00

Sorry, I overlooked that question. The C-Spec SM isn't freely distributed but the OM is if you didn't get one. Belt tension specs can be found in both.

Every year, I would organize our shop manuals and when a previous year got superceded by the next, I would throw it out. That's how I got my 2014 Bolt manual and all the manuals for my older bikes. Unfortunately, paper manuals were replaced with digital around the time the C-Spec came out so I had to buy mine. I haven't had to organized them in years since we haven't needed the space for more but I'll take a look in case someone ordered one since then. On the bright side, we've never had to do any repairs on a Bolt other than general maintenance and accessorizing.