Question regarding THF/COR/RNG (noob returning)

[Malithar]

1. Is thf and / or COR in any way a desirable DD end game? assuming they are geared properly?

Geared and played properly, both are capable of respectable numbers. Your DPS will be more of a supplemental nature compared to a main job DD though. The problem with the two jobs are more community based than performance based. Thf is commonly thought of as TH only (though a good deal of recent content does benefit from TH) and Cor has been pushed to the realm of a mules job, except for some of the most devoted players. With that in mind, you may have issues finding groups that take you seriously, or take you at all over someone's mule Thf or Cor.

Cor specifically has taken a backseat lately in the buff department, Geo and Brd are both typically preferred over it, however some of it's luck based JA resets and such are still desired and helpful, if they work, in content. Specifically in Rng setup parties, Cor is very desirable for Courser's Roll though. Both benefit from easily taking a /Dnc sub and benefiting the party through Haste Samba (if your setup even benefits from this) and steps.

2. I know about the recycle trait but as someone who is interested in playing RNG and COR, its seems a bit of a dead end if i want to play using a gun, as ammo is not on the AH? would i have to level ALC to craft my own ammo to even hope to enjoy the jobs end game?

Some of the best ammo is available through other means, specifically plasm, plasm, and sparks ammos. There are some crafted ammos as well, but those are far weaker than the other options.

Crafted ammo here, here, and here. As you noticed, the AH isn't very populated with them. With the sparks bullets beating them, there's not much reason to bother with them, IMO.

[Afania]

Cor specifically has taken a backseat lately in the buff department, Geo and Brd are both typically preferred over it, however some of it's luck based JA resets and such are still desired and helpful, if they work, in content. Specifically in Rng setup parties, Cor is very desirable for Courser's Roll though. Both benefit from easily taking a /Dnc sub and benefiting the party through Haste Samba (if your setup even benefits from this) and steps.

Just sharing some opinion about all that "GEO is a better buff job than COR!" floating around recently. Pure support wise, while GEO buff/debuffs are potent than COR buff, and being a more versatile mage job overall, having limited buff slot is still one major weakness. On the other hand, COR is better as a job to do multiple buffs for different pt/jobs, in fact it's a better job than BRD on this aspect as well, thanks to 8+ min roll duration.

For example, most Incursion pt tend to put Crowd control jobs like RDM or BLM on different pt from DD pt, and they tend to ask for macc buffs to land stuff on higher ilv. On COR I can just do macc roll on 2nd pt, and switch back to DD pt for double DD rolls. In fact I can still do mage rolls for mages in the DD pt. On GEO you'd have to sacrifice a buff slot for macc/meva-.

With PR job points category COR buff can stay longer than 8 min, just switch to 2nd pt before NM, macc roll can stay pretty much the entire duration of the fight without the need to reroll.