For days trips it doesn’t matter much, any old backpack will work just fine.
For water, just buy a cheap bottle or bottles of water in your favorite sizes from a grocery store or gas station and then reuse them forever. They are just as durable as any water bottle, a tiny fraction of the weight and cost. The “smart water” https://www.target.com/p/smartwater-1-l-bottle/-/A-12953554#lnk=sametab bottles have threads compatible with the https://www.rei.com/product/103050/sawyer-squeeze-water-filter-system water filter and I think conventional 2-liter bottles also do. https://www.rei.com/product/890900/sawyer-mini-water-filter is the lightest water filter.
The lightest and least expensive light duty stove is a cat can stove (or potted meat product if you don’t know any cats) https://andrewskurka.com/how-to-make-a-fancy-feast-alcohol-stove/
I just read that article for the cat food can stove, that's pretty damn cool and I definitely want to try it. I'd be a little concerned about accidentally crushing the can and then being without a stove though. I'm also curious how much heat this gives off, and how much fuel you would need to carry to use it over multiple days. One of the things I like about the MSI Reactor is that by all accounts it can function effectively as a mini space heater if you need to warm up quickly. It also has a bit more versatility in regards to what you can do with it. The cat can stove has no temperature control and doesn't accommodate smaller or larger pots without modification.
I do get where you're coming from with the water bottle method as well. I've definitely been leaning towards a Camelbak system just because it seems like the easiest method (not having to dig a bottle out of my pack whenever I want to take a drink), but the simplicity and cost efficacy of a simple water bottle method does certainly have its merits.
Preface to information and rants. Some people bag peaks or section hike or kayak. I decided to make tea from every lake in my local mountain range, and with the trips for that, general backpacking, weeks of wilderness archery hunting, and general use for hiking just for fun I have a couple hundred uses on my super cat stove. I even used it snowshoeing in 0F temps once, just flopped into a snow drift and took in the scenery while it boiled. I love it and my GSI kettle and my only regret is how little use either has gotten.
The ethanol burns and makes heat, just not as much as gas. I stepped on and crushed mine once, it is aluminum, I just squashed it back into shape and it worked just as well. Looked a little squashed still though so i made a new one when I got home. Mmmm potted meat product.
You need about 1oz fuel to conservatively and reliably boil 16oz water, or to unconservatively boil 1qt water or at least make it hot enough to disinfect it and be quite painful. Not much nuance, just fill the stove to the bottom of the holes, catch it on fire, and take the pot off when it goes out. Figure 2 stove burns a day, multiply your trip days by 2, you need that many ounces. Never confuse your denatured alcohol bottle with your vodka bottle or water bottle (since you are using cheap grocery store bottles for all of these).
Most backpacking meals consist of boiling water to rehydrate dried food, or to make hot drinks, so it works great for that. Most backpacking stoves are tippy, slidy, and narrow and not great for cooking anything fancy, and doing dishes sucks, so frying eggs or whatever is not common. Also the cat can stove doesn't put out too much heat so there isn't really a reason to throttle it. That said, some people make a dedicated "simmer stove" with just a single ring of holes and bring it along side. Two cat can stoves is not a great increase in cost or weight.
Holy crap you want a heavy $270 stove? You are being sold a load of something smellier than denatured alcohol. Maybe for a shoulder season solo Yukon mountain wilderness adventure.
Backpacking stoves are efficient and don't put out a lot of waste heat, so make poor space heaters. What space are you gonna heat, your tent? If you aren't careful you are as likely to melt a hole in it, burn it down, or asphyxiate yourself. A more common and better emergency use is to boil water to ingest (it does the most good on the inside) or to fill a water bottle with boiling water and put it in your sleeping bag wrapped in a spare shirt or sock or something. So not much advantage there either.
Essentially every backpack made in decades has a water bottle pocket on each side, and some also have them on the shoulder straps or hip belt. You will be doing something other than hiking 20 hours per day so you have plenty of time to take a 5s sip, adnt that would be true even if doing 16 hours per day.
When I was a young consuma sucka I carefully researched the ultimate hydration bladder, and proudly took it with me backpacking. On the first day I set it down on a prickly bush while I was filtering water and it sprouted a giant leak. I didn't have a spare. Since then, I have believed in always having a spare, and only using cheap plastic water bottles. I favor smartwater bottles or 2 liter soda bottles because they fit the threads on my Sawyer water filter. My smartwater have been dropped on rocks, branches, prickles, and everything, often from height, and have curiously never leaked even once. They are so dirty and beat up that other people won't drink from them.
Camelbacks:
leak if not treated carefully
expensive
heavy
inferior
Cheap plastic bottles:
don't leak
cheap
light
fit Sawyer walter filter threads for certain bottles
superior
Return the camelback