Missing Header Bolt Size?

[BlackZR1]

Good Evening guys,
What size is my missing header bolt? Looks like an M8 x 1.0 (fine thread) but I tried a coarse and fine thread and neither wants to start.

I also notice that the bolt below has a collar (like a 3/4" long spacer) on it. What is the purpose of the collar? Is this a special bolt?

For extra credit, what size is the small bolt that secures the aluminum cover over the throttle cables at the throttle body? The 2 nuts on the side are 4mm. My missing small bolt in front seems like it should be a 4 mm, but I tried a 4 mm and it didn't want to go.

Thanks,
Roger