I recommend reading "beyond backpacking". By ray jardine. It's both practical and philosophical in theory of going ultralight. He's done the triple crown, and a few others. Do a few shake down hikes and document what u never used, and eliminate. I've changed systems at least 7 times, so enjoy the ride as u discover what HYOH really means.
What underwear? Kidding... I wash my running shorts (acting as my underwear) every few days.
Each person has his own system, but one idea is to have what you wear, plus one change, plus something to sleep at night.
For an example of clothing over the different seasons, take a look at the link below. Of course, that is what works for that particular person, but it may give you a few ideas. He also has put together a gear list.
Some of the stuff might get lost in that oversized packEven if I stay within my weight goal?
Going as lite as possible allows you to enjoy the hike. Just don't go so lite you are not prepared for the conditions you will be hiking / camping in.
Lots of good info here and on Whiteblaze on how to reduce your pack weight.
As suggested, get a scale that weighs in grams and ounces. One that weighs up to 5 pounds is big enough. Make a spreadsheet and weigh everything you plan on taking and then take a hard cold look at the spreadsheet. If you are packing something that weighs more than that (other than food and or water) its too heavy and you need to look for a lighter weight solution.
You asked for advice, so here it is. Understand that what is important to me may not be important to you, etc. Anyway, I see way too much redundancy in this list. You don't need both a notepad and a logbook. Choose one. Discard the hatchet and pick the knife or multi-tool. Better, discard all three and find a lightweight folding knife with about a two and a half in blade. Discard the sharpening stone - you can borrow one a various stops if you really need it. You list "compass & asthmas" and a "button compass". Pick one. You don't need two compasses. Emergency crank radio - too heavy, just get a small radio that meets your needs. You list two books and the bible. This might be a good time to see if a Kindle (the one's without the back light) and see if you can download your book choices to it. The battery life on those are about two to three weeks. You'll need a padded case for it, but it will still weigh less than one book. I know you can download the bible to it, pretty sure you can find a downloadable guide to edible plants. Not sure you really need the US Army Survival, Evasion and Recovery book. We promise not to shoot you if we see you on the trail!