1. Best PvP set here is the star 2 officer gear that you buy with AP and Ceranium Medals (also requires having abyss rank of star 2 officer at least ofc). There is other sets like rank 1 but not worth it and doesn't have set effect. There's general gear too. But don't bother with these, start off by getting your starter gear by farming Blood Marks from Katalam/Danaria camps, then go to sieges, arenas, PvP instances etc... There is even some PvE instances like Steel Wall Bastion requires 24 coordinated people, and some others like a solo instance look up any source of AP and Cera Medals. (There is also key farming in the Eye of Tia for AP) *There's some camps that sell the gear a bit cheaper in AP I think, I don't remember well, and which camps or which gear ask people or research.
2. You can level up Alchemy to craft them if you have the will and time and kinah. Also leveling up you Gather stuff so you gather yourself you components. I think the end game highest levels crafting scrolls for best consumables are only a drop or buy from broker people that dropped it I'm not sure. Me I don't bother with all of this, I just farm a bit kinah and buy my consumables from broker more convenient and comfortable for me
3. There's manastones (and composite manastones for double stats), but remember that if you fail socket, every previous manastone socketed gets destroyed and basically it's a reset. You have enchant stones that you either drop in bags or by disenchant some gear, you can look up in forum I think they posted somewhere about how the rates kinda work but it's still RNG like everything else. Godstones that you get either as rewards from bags or PvP quests and drop from any mobs, the ones from quest are not tradeable but quests are repeatable. 100% supplements for manastones are in shop so either you buy them yourself like that or from broker, if not in broker you can ask in chat for people selling them. Normal supplements for both manastones and enchant, I don't know about them a lot, for mythical ones you can trade Blood Marks for them (or Ancient Coins for a very good starting PvE gear), I don't know where you get eternals. There is a new item called plume that's new in this patch, very rare drop or very expensive to buy, you upgrade it with Tempering Solution/Serums (that are also super rare to drop usually on bosses of late game instances and sell for a lot of kinah also used to enchant accessories for more PvP stats). when you upgrade them they give good stats (HP+Attack or HP+Magic boost) but the catch is the more you upgrade the more chance of fails and it destroys the plume. TL;DR don't bother with this until very late like the last thing you bother with, but if you loot any of those 2 items leave them or start trying your luck or you can even sell them.
4. You can drop stigma as general loot from anything, always try to look for them on broker for cheaper first, then if it's really an important skill I just buy from NPC, but usually I just keep checking broker if someone is selling what I need. I think yes the NPC do sell all of them for every level, There's also Superior Stigmas that you start getting after level 45 you buy them with AP, and you need some quests to open their special slots (once slot is open you can put a normal stigma in it not necessary a superior one, but generally every class has a stigma tree that requires some so depending on your class and build). Superior Stigmas you can buy lower levels then upgrade it to next when you can for cheap, don't buy the next level superior stigma from scratch just upgrade the previous level to next in the upgrade NPC (the total first stigma + the upgrade cost to max level is same amount of AP if you buy the max level one directly). There's some camps in Danaria ( 81 and 89 ) that sells max level stigmas for cheaper price than normal NPCs.
5. Gotta be specific also I think I answered some in previous posts. But in general It's new content for PvE and PvP, with new maps and other stuff.
6. I don't think the server is pay to win, since they don't sell gear directly or temperings solutions for enchant plumes and accessories, you can check the shop yourself, there's only cosmetics and boosts and mounts etc... what is a bit bothersome is the 100% manastone supplement for socketing but it's not really that big of a problem and you can buy them from people selling them with kinah so you can basically play the game without paying like I do cause I can't spend real money. A real pay to win server is like official and some private that do pay to win events and sell the temperings directly in shop that just break the PvP balance cause you have whales with all +5 accessories and plumes and you can do nothing to them if you are a f2p player. So no issue in that regard.