Mitch - Jumping in with both feet, first overnight trip is a 21 day hike! You're in for a real treat.
+1 -- "Also, try to get out on an over-nighter before your trip. It will help you figure out if something isn't working well."
Trash compactor bag - I assume you mean pack LINER, not pack COVER. It will shred on the outside, and there's no need to keep the outside of your pack dry anyway - you just need to keep the inside dry, ESPECIALLY your wool top and long johns and down stuff. Trash compactor great on the inside of the pack - I've been using them for years, one bag treated with a modest amount of care easily lasts me an entire six week long trip.
Ditch the ground cloth.
Ditch the spare running shorts. And I'd recommend you'd bring light rain pants instead, they'll work for rain and for evening warmth. Given that you don't have a lot of experience as a backpacker, I recommend being conservative in terms of preparing for things that could cause you trouble. It's absolutely true that weather in August is *usually* clear and dry and beautiful. But I've certainly had a few serious storms in August in the High Sierra, and it could happen to you. A friend had a 68-hour August monsoonal storm in the Kern drainage - very unlikely, but as a beginner you might err on the side of being over-prepared for safety.
Gloves - Bring a lightweight pair of "liner" gloves. Expect night-time temps in the 30s.
Sunglasses - reduce risk of cataracts, personal choice.
Ditch the head net. Given the anemic snow pack this year, bugs should be essentially done by mid-August.
Camp suds - 4 oz? -- whoa, way too much. I don't carry ANY soap in wilderness areas. Never ever use soap where it will enter surface water. Wet wipes or a little alcohol are a better option for health related hygien. Don't worry about body odor and filth - that's just part of the deal.
Deodorant - Arid Extra Dry Cream, transfered to a tiny pill container, will weigh 0.1 oz. Same for Body Glide.
Rope/cord - a short length of light cord might come in handy
Food - There's a ton of info on these forums about food, you can learn a lot by browsing. One data point -- Jim and I each eat 26 oz per person per day while backpacking, strongly skewed toward foods with HIGH FAT CONTENT since fat is 9 calories per gram while carbs and protein are only 4 calories per gram. Therefore you'd need to take ~2 oz of noodles or oatmeal to get the same oomph you'd get from ~1 oz of fatty food. Chocolate, cheese, salami, nuts are staples. Choose high-fat crackers, cookies, bars instead of the low-fat varieties. Pack the heat-sensitive food inside your pack such that it is buried inside clothes/sleeping bag so it doesn't melt/spoil. We don't cook, but that's a personal choice. It's easier not to cook, it doesn't attract as many bears, you don't have to mess with dirty pots, and cooking doesn't add any calories, just adds water. Fatty foods don't need water added. Take enough protein, focus on fatty foods for calories, and reduce the carbs to whatever it takes make you happy. All that said - the type of food you'll find appealing is very personal, and you'll learn that over time via trial and error.