i) Not that ppl dont wanna sell it, mostly they shout in trade channel or stall at Navea (stall area) due to the taxes in AH too taxing (if you're poorfag seller) & low drop rate. Lvl 60 recipe is pretty expensive so it's best to self hunt via grind on Otherworld Mode dungeon like Helonia, Miners Steppe, etc... Not sure about regular Hell Mode though. Current Dungeon Entry UI have list of boss you will encounter together with their skills & drops on each mode. You can check it out through there.
As for World boss, lots of useless junk. Most people hunt 'em mainly for costumes and they die like... less than 5secs LOL (Pray RNGesus for this one)
ii) There are 2 types as far as I remember. One is Worn Out Card, another is Enchanted Card
Enchanted Card = an End Card that you can slot into the respective costumes without needing additional stuff (refer card description) This type of card have 2 types.
- Dungeon/Chests Dropped Card
have 1 stats,
- Fusioned Enchanted Card (Fused from Worn Out Card)
have 2 stats.
Worn Out Card = A fuse Card to get a Fusioned Enchanted Card with additional stats, Where you need an "Advanced (respective card. right click Worn Out Card for ref.) Enchantment" and 5 Ancient Eido Fragment.
But prior to this step, you need: 1 Fusion scroll & 5 (respective body part cash item card) Enchantment
to get the "Advanced (respective card. right click Worn Out Card for ref.) Enchantment"
So in terms of best card : Fusioned Card > Dungeon/Chests Dropped Card. So if you're extremely rich or RNGesus shines upon you or both, Worn Out Card will be your best option. There has been an interesting talks circulating in-game that there is a chances to get the Enchanted Card (that have 2 stats) from Dungeon/Chests, but I have yet to see any proof of this.
iii) They do, especially SkyTower. 4F onwards if you have less than 4~5 party groups. Don't bother.
Infernal Abyss = Race against the clock & reach as deep as possible. More chance to get Zaahir's Key/Key Frag. Recommend to equip Flame elemental armor if you enter this dungeon.
SkyTower = Reach as high as possible with 40 ppl in the group. Floor progress of the group is saved for 2 days & will be reset every next week (it supposed to work this way). So there's no need to actually rush for the current released content of amount of Floor.
Hopefully. There's a slot, lack of Range DPS at the moment. Due to my current state, I mostly online after 10pm for 4 days every week and tonight is one of the night. Cc:
Coldf3ar for invitation.
PortSkandia contain most info that you need (here)