While it is actively fermenting, it is putting off a lot of CO2 and oxygen isn't a concern.
I put an airlock on it, but I don't fill it with vodka until my last nutrient feeding.
So as i understand what you meant, i should buy a 1.25 gallon so i can ferment in that, and then move into the 1gallon carboy?
Correct... or just go to Home Depot or Lowes and get a food grade 2 or 3 gallon bucket in the paint section... that is where they are at. Use that as a very inexpensive fermenter where you can easily make larger than your carboy you will rack to and you have a lot of space for fruit additions if you go that route. I say get the 3 gallon size as it uses the same lid size of a 5 gallon, if I remember correctly.
What did you mean with mixing in enough o2 to get the mead off to a good start? Just shaking the bottle after i put honey and water in?
You can certainly do that. I would recommend a wine whip (think a paint stirrer) on a drill where you can really get a lot of O2 into the must.
If i want to get a sweeter mead how would i go about that? Ive read some people use campden tablets to halt fermentation, some backsweeten with artificial sugars after its fermented dry, whats the best tasting method? I assume backsweetening is the simplest.
Best tasting method is personal, though my choice is always honey... because I am making mead. Non fermentable sugars will work and I've heard that Erythritol is the closest to the flavor of table sugar, but I don't really know.
You have two ways to deal with this. The easiest is to let it go dry and the use Potassium Metabisulfite and Potassium Sorbate to stabilize the mead. Wait 24 hours or more and then back sweeten with honey. I would suggest get a powdered Potassium Metabisulfite in place of Campden tablets as it is just easier to work with. You want a small digital scale accurate to at least 2 decimal points. IMO, get the best you can reasonably afford if you expect you will continue making mead for a while.
The other option for sweetness is to have enough honey in there so that when the yeast stop, there is left over sugars. If you want to go that route, I would suggest an ale yeast like SafAle S-04 and expect it to eat upwards of 14% ABV so you have to have more sugar in there to hit your desired sweetness. I mention this because it is an option, but I would really recommend the back sweetening because this method really requires a high O2 at yeast pitch and starting out you want something easy to deal with.
Also i have a question about clearing, do i just wait? will it clear itself? do i need pectic emzymes?
You will only need pectic enzyme if you are using fruits or fruit juice. For most meads time will clear stuff out. Mostly, but not always.
If your batch is only 1 gallon, you should be able to stick it in the refrigerator to "cold crash" it. That will help items drop out. If that and time isn't working fast enough, you will use fining agents. There are a variety of them available. My recommendations fall into two camps.
Vegan or not.
If you want vegan, then you will likely use Bentonite first and once it has done its job, you rack the mead to a new container and then use Sparkolloid. When Sparkolloid has done its job, you rack again to a new container. Expect each of these to need 1 day to 1 week depending on how cloudy your mead is.
If you don't care about vegan (probably don't as you are using honey from the enslaved bees) then I suggest Kieselsol and Chitosan. These work incredible. You stir in the proper dose of Kieselsol and then 1 to 6 hours later stir in the proper dose of Choitosan. The results are impressive in a very short amount of time. Give it a week or two for everything to drop out and then rack to another container.
In either case, you will want to have lightly stirred the mead to degas it of CO2 before using fining agents as they work so much better that way.
Bentonite is a special case where you can add it at the very beginning of fermentation and it will start working on stuff as it ferments. It really is a nice choice. I sprinkle in the recommended amount dry at the very beginning and don't bother making a slurry ahead of time.
Obviously some of this is going to require you to look these up and make your own determinations.