That are a lot of questions. 
I try to answer a few, but keep in mind, it is only my opinion/advice.
1. It is possible to get endgame gear as f2p, you just need to invest more time or concentrate it on endgame. I did finance most of my gear at the start with farming gold and selling it in auction house for dias. With those dias, I bough gear. After some new upgrades, I was able to do certain inis with my guild and able to farm new gear.
2. No guild is really thinking, that you will be dead weight, only if you behave like it. As long as you show motivation and try to farm and play together with your mates, they will appreciate it. This is a MMORP and you need to play with others to achieve the highest inis. There are a lot of support combos. Most of them can be played with a low gear (as long as you have enough HP to survive certain attacks), because you will buff your mates or debuff enemies.
Some supps and how good they are in my opinion:
- Best supps: wl/d, wl/p, s/p
- good supp: wd/p, w/p, ch/d
Keep in mind, in some inis/situations, certain supports are more needed than others. There are also other good supports, but I cant comment on them (e.g. b/p).
3. Try to "hunt" one in auction house, sometimes you can get one very cheap, but you need dias for that. As long as you are not "good" enough to be a dps, you dont need a endgame weapon.
4. I am a main tank and only using golden repair hammer. Over the time, you have enough, if you grab your free stuff dayli.
5. Ehm, no idea tbh. Just get one set and build it to farm anything like gold.
6. In the end you always want your main stat doubled, but like I said in 5., your first gear is only for farming. You can use crap stats too.
7. If you want an only support gear, go for cloth and just use crap stats. You need HP to not die everytime. When I play supp, I often use my tank gear, because my accessoire gives me enough HP. Focus on a farming gear first and play a support, which is needed and maybe isnt played in your guild.
8. Permanten aoe-auras are good, but as you already said: wd and just spam power of the wood spirit. You may lack enough dmg at first. Wd/r is good, because it deals kinda double dmg (b/wd too, I think).
9. It is needed, when you want to go higher inis, but it shouldnt have a priority now. Just do it, when you are free e.g. afk or on a weekend.
10. sry no idea
11. I think character, but again, sry no idea.
12. You can get buffs for 2hours: droprate, exp, tp. There are some guys outside atlas. Use it to farm gold or level classes. Otherwise do WB, it gives arcadia coins, which can be converted into mems, which can be converted into dias.
13. I think even r/k as tank is played with plate, because of the base armor you recieve. But you should focus on one gear at first.
14. "crap gear" like second gear for support or for newbies. In the end you will have as much as you can of your main attribute, like i said before.
15. Have fun, I guess?
