i agree, don't use portable a/c's, a window A/c is more efficient than those things.. but yes mini splits or small a/c setups are ideal because they're so efficient. Its a really good idea if you plan to use a lot of lights to yes use cool tubes and put them on a seperate loop going outside, and keeping your room completely sealed.
now you can use co2 if wanted once you learn to use your equipment
as far as medium goes you can go with soil or hydro
I like hydro because the medium is inert, soil is organic and brings unwanted pests in. i save the organics for outdoors. The easiest method in my opinion is hempy. it uses two small holes put up about 2" from the bottom of the pot to create a resevoir. this resevoir wicks moisture up for the hempys to feed on and is technically hydro because the medium is hydro
you can do this with soil too though
other setups to look into are rdwc, drip, ebb and flow, or aeroponics
i like the idea of drip with coco in airpots the most because you get air through the medium by using airpots, with the added benefit of coco and ultimate oxygenation in the rootzone, in my eyes, a cheap form of aeroponics