Fellow Texan, here...
Lincoln and BAICA are mentioned throughout the forum. I don’t have experience with schools here, but if you search the site for international schools, threads pop up with conversations about these schools that may have information that interests you.
Best advice, come with flexible minds and adapt to the foods, culture, etc. Take the time to get to know the city and what it has to offer. If you are planning on staying long term, take to time to visit other tourist destinations in the country. If you are moving because of employment, find out what they pay for (services, moving expenses, relocation expenses, etc.) and what they have to offer as far as information goes.
Coming from Texas where most of my shopping was done at HEB, I was of the mindset of shopping in a one-stop shop like that was the best solution. Here, I shop the small shops and only when I need to. Carniceria for my meats. La Granja for my poultry and eggs, and maybe my cheese. Fiambreria for the meats and cheeses and maybe some olives and other brined goods. The dieteticas for breads, oils, milk, butter, seeds, beans, and maybe peanut butter every now and then. The verduleria for my fruits and veggies. I pretty much only go to the big places (Jumbo, Disco, Coto, etc.) when I need something from frozen goods, soaps (but that’s also at the dietetica), or canned goods (which is rarely).
Also, coming from Texas where driving everywhere is the norm...this will depend on whether you will be using a car (purchasing or bringing it down here). We prefer to use the public transport or walk (or Uber/taxi). In any case, BA has buses, subways, trains, taxis, and you can get pretty much anywhere without a car and the expenses that come along with it (cost for parking, fuel - pay by the liter - not the gallon, bumps/dents - btw we see bumped cars quite often when parallel parking).
Any other specific questions, just ask away. I’m sure someone will answer. I know nothing on the ballet front. You may want to do a google maps search for that. Reviews in google maps are used fairly well here. Best of luck and welcome.