Tent: I wouldn’t worry too much about the tent at this time. I used a Big Agnes Seedhouse SL1 and was very happy with it before going to a Gossamer Gear SpinnShelter – Alpinlite Bug Tent 1.25 combo last year. Big Agnes makes good tents.
Footprint: I had over 140 nights in my Seedhouse SL1 and never used a footprint. There were a few times that I was worried that I would get a puncture in the floor, but after all of that use, the floor still looks like new. If you really think you need a footprint, look into using Gossamer Gear Polycryo or Tyvek.
Canister Stove: I understand about the Tri-Ti, as they are quite pricy. I tried several alcohol set ups a few years ago and went back to my Snow Peak Gigapower, but someone finally convinced me to try the Caldera Cone and I haven’t used the canister stove since. It’s just something to look into down the road someday.
Knife: If you like a knife with a clip, there are probably some lightweight options that have one. One nice thing about the Gerber is that it is made in the USA and the Spyderco is made in Japan.
Scoop: That is a good idea when you are wondering how going without something will go, take it and try not using it to see how it goes. I can see where in some soil types you could have problems. I hike where there is normally a lot of soft, wet soil and forest duff that is very easy to dig in.
Big Zip Platy: It could be a personal thing, because I am not a huge fan of hydration systems, and have always been leery of the zip on those models. You just have to evaluate if the additional usefulness of the zip outweighs the additional weight. This will probably have something to do with the water sources that you normally hike around, (rivers, creeks, springs (pipe?)) etc.
Filter: I have hiked about a thousand miles since giving up my filter and there were only one or two times that I wished I had it. Of course it has a lot to do with where you get your water from, but I have always felt comfortable with Aquamira. There are other choices too, some people love the steripen (tried it - it wasn’t for me), miox (tried it – really wasn’t for me) so you might look and see what works best for you. I have been happy with the drops and I know that is what Ryan Jordan uses and he is an expert in Backcountry Water Treatment (his PHD is in Biofilm Engineering).
Like I said earlier, I don't like hydration systems so I use 2 one liter bottles, generally Gatorade bottles, to drink from. I just mix the Aquamira in the cap, dump it in, shake, and let it sit for 15 minutes.
Pack Cover: I know the feeling about wanting to stay visible. There have been a few times where I didn’t have any orange on and was concerned for my safety. I really liked my MLD pack cover, so I made one just like it out of blaze orange silnylon (my fist sewing project). Mine is a little heavier because I couldn’t source shock cord as thin as the stuff MLD used. I wasn’t implying you shouldn’t take the pack cover, just that it seemed a little heavier than most.
Extra Batteries and Backup Light: I think I would keep the headlamp as well. I just find them so much more usefull than a flashlight because they are hands free. Your headlamp probably has a small LED battery indicator on it. I would just check that before you go and as long is it is green, I would think you would be good to go.