1. Its a park, sit where you want. There are grandstands, but you really should walk the track.
2. Yes, and FM radio
3. You can walk the entire track, and pits. Food is in the pit area, toilets are around the track, you can buy drinks around the track from vendors.
4. There is lots of room, Mosport once held the record for the largest sports crowd in CDN history, 110,000 (76 Canadian GP)
5. Main straight into turn one. Moss corner at the farthest end from the pits. This has a descent and braking into a double hairpin, once described by Niki Lauda as top ten corners in all racing. Great spot for passing.
6. Ear plugs, water, hat, sunscreen, sunglasses, camera, cash. Preferably, buy some FM radio safety ear muffs, so you block out noise, but can hear the announcer. the track has loudspeakers, but they are useless outside of the pits. Turn one has a jumbotron, but only if TV is covering the races.
Mosport is one of the world's best and classic tracks, but the GTA has learned to ignore it in favour of watching drugged up players in US team sports in overpriced arenas.
It is NOTHING like TV...the sound is visceral, watching guys race in person is addictive. It's a nice place to spend a day.