I just recently hit 50 on a couple of my FFXIV crafting classes

99% of craft mats up to around level 20 in all crafts can be purchased, quite cheaply, from NPCs. The one exception that immediately springs to mind for me is Aldgoat Skin. If you have retainers unlocked then you can try selling the other items on the MB. If they seem fairly worthless, which many of them are, then vendor them. You don't need those Animal Skins or Animal Hides because you can buy Leather and Hard Leather from an NPC for probably less than the value of the shard it takes to make them.

The description on fish will say whether or not it is a crafting mat. I'm not sure how long I juggled retainer slots around before I realised that!

I just recently hit 50 on a couple of my crafting classes, as well as my FFXIV Power leveling gathering classes. I've got a way to go on the main story quests before I can do Heavensward content. What things should I be sure to do at level 50, aside from continuing to level up?

Focus on completing your MSQ, you'll need it to continue making any reasonable progress with your crafters unfortunately. Once you get a ways into Heavensward, be sure to do the Moogle quests to unlock their beast tribe content. It gives pretty good XP and you'll need Kupo Nuts to trade for Glass Fibers which are needed to make end game crafting and gathering gear.

I have been working at leveling my crafters diligently since 3.3 came out through Moogles and Ixals as well as levekits. In this time, I have been capping red scrips and gaining blues with BSM, which sucks. I have come up with a sort of rotation, however, and can usually HQ/max collectability without issue. I have a few questions though. Is Comfort Zone only useful if you can use it twice? It's a net gain of 14 CP, not enough for a touch. I have tried using CZ in my crafting and it hasn't done anything for me. Also, if I have enough CP for a Basic touch two steps before BB (including GS step), should I use 18 CP on a basic versus a hasty, or use a hasty and Innovation instead? I haven't been crafting very long and I'm not really sure what to prioritize IQ stacks over or below.

It's a net gain of 14 CP, but if you already have leftover CP at the end of a craft, it can help you get a boost.

For example, if your rotation leaves you with 4 CP at the end of a craft without using Comfort Zone, using Comfort Zone will let you get an additional basic touch somewhere in your rotation.

You should know how much CP you have leftover if you only use hasty touches in your rotatoin and every 18 leftover CP should be used on a precise touch on Good/Excellents.

If you get near the end of your quality phase and still have Basic/Precise touches to use you can use them as guaranteed touches instead of hasty touches.
I don't have the data on me, but I believe one IQ stack is better than a Innovation in the finisher, but if you believe in RNG you can just hasty touch to get both the IQ stack and innovation. I personally prefer to play it safe and use it as a basic touch, but I wouldn't say risking it wrong, more of a personal preference kind of thing.

How important are the i195 tools vs the i200 Augmented tools? Or rather, how important have meldable tools been to hitting previous crafting caps?
I'm trying to craft all my own Ironworks gear (aside from a couple of off-hands to bootstrap myself) and while I can afford most mats easily, I'm still a little gated by Moogle dailies as buying all the Glass Fibers I need FFXIV Gil guide
outright would bankrupt me a few times over. With that in mind, while I haven't done the math yet, I should be able to buy a few tools worth of Goblin cups between switching out my Specialists (as in, I would be able to cap RS a couple of times over before having enough fibers to move on to the next class). That would reduce my time to omni-3*, and significantly reduce my material costs. But if I do that, then I won't have meldable MH tools for probably 4/8 of my crafters, and while I generally haven't been melding tools, if that's been needed in the past to hit targets, then I'll have to suck it up and get materia or something with my scrips instead.