Glad to see you've learned something straight away! Good job! Nice to know that my stickied post has helped too.
The TM Warthog should not be an impulsive buy. It is a good piece of kit but an expensive kit if you aren't using it. If you are going to play with DCS A10C however, there simply isn't anything better.
Regarding you question of what to learn, I believe you should learn about your aircraft first, then the weapons. Personally, I learn about 20% by reading, maybe 60% by doing, and the rest by experimenting. I am more of a do-er, I learn things by doing. In fact, I prefer to fiddle with stuff first, THEN read about it
Anyway, start off with my A10C newbie guide, make sure you are more-or-less familiar with the cockpit. Even if it takes you a minute or so just to locate a particular switch or button, the important thing is you know which side of the cockpit it is located, and the general place where it should be.
Then take a clean aircraft (no weapons, 25-50% fuel) up for a spin. Take off, follow waypoints (even if it's just one or two), have fun in the air, try a few maneuvers and observe the aircraft why doing so. Then come back in and land. After that, take a fully-loaded aircraft, doesn't matter what you have on your wings as long as the MAX % on the Payload screen is at or close to 100%, adjust the fuel to add the weight. Do the same thing you did the first time, and note how the aircraft handles differently, more sluggish. Take it in for a landing too, and note the change in your landing parameters. The idea of this exercise is to gain appreciation of the aircraft's limitations.
Once you can take off and land confidently well, it's time for the fun bits --- the weapons! Sim has made an excellent guide here
and again, I would suggest you make a "weapons exercise" mission that starts you in the air, facing the targets, about 15-20nm out. I would suggest the targets be at the range north of Bantumi, makes it easier to spot them. Pick a weapon of your choice and practice using it. As I get most of my "fun" by blowing things up, I feel it is important to get to the "bad-ass" bits early.
This is also a chance to play with the weapon profiles and get to know the DSMS and how to change stuff via the Profile scree or the Inventory screen.
By this time, you know how to fly the aircraft, navigate, and blow stuff up. Good. Now the icing on the cake. Radios are mostly useful if you want to interact with Tower/ATC but since they're usually more trouble than immersive, I don't bother. Most use for radios is JTAC and Tanker calls, and the radio intercom for refuel/rearm from the ground crew.
If you want a bit more of a challenge, change the targets in your weapons exercise mission and put in some SAMs or AAAs. Time to practice ECM and defensive maneuvers!
But always remember, at any time you are confused or lost, the forums is here for help and amusement, and drop by the TS server and you might catch one of the regulars online. Any of them/us will be happy to show you what little they/we know
Welcome to Warthog crack!