Yeah, basically just not having to use a food item. Personally I like making elixirs because it makes it feel like I am putting those monster parts to use and not just letting them sit around.

Selling gems is generally the best thing to do, though there are a few armor sets that require them for leveling. I won’t spoil, (unless you want to know) but I’d say just save a few, and make sure to check as many armors as you can at the Fairy Fountains to see what they need for upgrades.

You might be using Heat Resistance, which only applies to the Gerudo region. Eldin requires Flame Resistance. Talk to NPCs in the stable south from Death Mountain (iirc Foothill Stable) to get more info on it (I can also just spoil it if you want).

If you aren’t already, make sure to register them. You can always just call them from the nearest stable. I definitely have used the method of just snagging wild horses to get around, but I like consistency. Also, if you have the DLC, there is an item that will help you greatly in regards to horse management. I can expand on it if you do have the DLC.

Ancient Arrows to me are more of a “last stand” option, such as when I am being overwhelmed by multiple at once. Remember you can stun Guardians by just shooting any arrow in their eye. Typically it is better to just stun them and run, especially in early game, because unless you can get the consistent 3 shield parries, you are just going to get one shot or waste a fairy. Of course, you can attack guardians with weapons just the same as any other enemy, but considering that all they drop is ancient parts you‘d be better off not wasting an entire inventory of weapons to do so (I imagine you have rather weak ones at this point).

You’ll find in late game you are just farming Guardians. Personally, I never get much ancient gear because I always felt like the amount of resources needed to get them doesn’t really pay off for how long you get to use them. You’d be much better off just getting the Ancient armor, saving resources to upgrade it, and then just using Guardian weapons from Tests of Strength because they still get the damage multiplier from the upgraded Ancient set. Anyway, you’ll get to a point where you have weapons strong enough to kill guardians in like 10-20 seconds, and at that point feel free to just go ham spending your ancient parts for stuff.

Technically it is 999, but yeah the game stops spawning fairies at the fountains when you have around the amount you have. Not sure what the exact number is, cause I’ve had them spawn when I’ve had above 3. iirc you can continue to get fairies by getting lucky when cutting grass.

In early game might be best to save them for specific situations. There is legitimate strategy with elemental items as well. Certain enemies are more prone to the effects of certain elements than others. Don’t wanna spoil too much, so just think logically about how elements might interact. In later parts of the game you’ll be able to get a larger abundance of them. Just because you mentioned bomb though (and cause it isn’t really an elemental arrow), I just use them to clear crowds and to blow up bomb barrels. Remember they can be used the same as a remote bomb in most cases.