We did the exact route last year during the 3rd wk of July. Check out Caltopo for the trail maps.
First camp was about 9.5mi from Horseshoe Meadows TH. We pulled off the PCT to go higher to 11.5K because of the mosquitoes.
There are at least 2 creek crossing. Rock Creek was a challenge last year, but we found a couple of logs to use about 100yd upstream. The second creek is Crabtree Creek, which was much less difficult than Rock Creek. Then if you keep going on PCT and then join the JMT, you avoid any more creek crossing (albeit a small climb and ~0.7mi more). This year there appears to be less water, so it may be trivial creek crossings this time around.
We camped on Guitar Lake, but it was crowded at that time of the year, so plan on getting there early in the afternoon. There is also camping above it, maybe another 0.75mi on the trail and last year it had water.
We all carried 3+ liter of water, but it wasn't necessary, as there was a creek flowing on the top part of the 99 switchbacks. Still, 3L was enough to summit and then reach Trail Camp. Your mileage may vary :-)
Don't know about campfires, as we didn't do any and I didn't see anyone doing them either.
As for parking, I believe that you need a permit/pass. We used the Inter-agency Annual Pass.
