I'm glad to see you're planning this.
1) Yes. I plan to mostly do mail drops.
2) You don't have to camp at a campsite. I plan to do so as little as possible.
3) If you leave early like I plan, you should probably take an ice axe and ice traction aid. If you leave at kickoff or a little later, I think you'll be fine without.
4) That's a big subject. Basically, use a bear canister and keep food hundreds of feet downwind from where you sleep.
5) Don't worry about it. Worst that may happen is some assholes may throw something at you while road hiking. That happened to Lionking.
Most people here prefer trail running shoes over boots. The advantage is that it's much lighter and cooler, which helps prevent blisters. They also dry out a lot faster after creek crossings. The disadvantage is having to replace them several times on a thru-hike.
But I have no PCT thru-hike experience yet, only knowledge I've gained from places like this, and a little from the guidebooks.