1) I suppose. A single 18650 will last a looong time at the outputs a backpacker will need, but it's bulkier, and uses heavier batteries than, a AA version.
I've used a AA H52Fw with a rechargeable as my backpacking light for hundreds of nights over the last 7-8yrs, and aside from lighting up a campsite for a nighttime pic, have never once used H1 or H2. I don't do trips more than 7 days, and have never once used the lithium AA spare I keep in my "emergency"(first aid, repair, etc.) kit, either.
If you wanted a dedicated night hiking light, 18650 all the way, but for "normal" backpacking use, I don't see the point.
2) Neutral tint is, for sure. Some of the high CRI LEDs(including some Zebralight's used) have a reputation for crappy tint, and tint is what really decides how you see things, because it overlays, and provides contrast for, everything you shine the light on. I'm not familiar with them, so can't say which ones are preferable, or to be avoided. My plain "w" has been great, so I've never had reason to try other versions.
3) No. Unless it's just going to be used inside a tent, the floody is a lot better. A pure flood will require much higher output to see at any distance, go through batteries faster as a result, and still never really have much reach. The floody has more reach, and is also much better than a defined spot for hiking with. I have an older neutral Zebralight that's pure flood, and the Nitecore NU25, which is all the craze nowadays, and has both a cool LED with focused beam and a high CRI pure flood mode. The short version is that they are both crap compared to the Fw.