1. Water treatment: I use Aqua Mira drops for solo hiking. The set of bottles is light weight, costs about $15, and lasts me more than a year. For family hikes we take a Katadyn Hiker filter. My wife prefers filtered water, and I find it faster for two or three people than treating large amounts of water with AM.
2. Plenty of hikers don't cook hot meals in hot weather. The last thing I want at the end of a hot, sweaty day is a pot full of cheesy glop. Don't forget cheese, the little red baby bells will last a couple of days. Jerky is good, and gorp, and plenty of nuts and dried fruit. My favorite trail sandwich is a bag of tuna, several mayo packets, and a tortilla — works for lunch or dinner. Peanut butter will work, too, or Nutella. Flour tortillas are great for any of this stuff. We've also liked instant hummous with tortillas or pita bread — if you eat it for lunch the first day, bring a cucumber too. Makes a tasty high-protein meal. Chocolate covered espresso beans are my favorite caffeine supply device. But they might have a melting problem in the summer heat.
Overall I would think that you'd find meal prep easier without having to cook — at least I do under those conditions. Just realize that your overall food weight will be a little heavier.
3. I have and use all three shelters, depending on the conditions. In the summer, for solo hiking, I like my hammock — a Hennessy Explorer UL. It's eight years old and going strong, though I really only use it in the summer. I use a 3/4 length Ridgerest pad inside under my torso for warmth — you'd be surprised how cold it gets even in the summer in a hammock. The pad does double duty at meals and breaks and naps. The advantages of a hammock are: ease of setup anywhere there are two trees; weather protection; true sleeping comfort.
For the best all-around solo shelter, I would vote hands down for my Tarptent Moment. It's a single-wall tent with full mesh enclosure, great weather protection, and tons of room even for a large hiker (like me.) If I could have only one solo shelter, this would be it. Easy setup, good views, not too expensive, etc.
Good luck. It'll be a fun hike.