best advice I can give you is to download bru'n water. read the instructions and have at. I build from RO and keep Calcium Chloride, Gypsum, Lactic Acide 88%, and pickling lime on hand. Additionally my wife keeps Epsom salts on hand.
Most of the time I use the amber/yellow/dark malty/bitter profiles and mostly just try to get >50 ppm calcium in there. I use the lactic when needed (most of the time when making lighter beers) to get my pH down (predicted pH, not measured). I use pickling lime when needed (Rarely) to bring pH up in very dark beers.
I go back and forth with acidifying the sparge water and don't think it matters much with RO.
I would suggest getting a gram scale though. makes it easier when the water recipe calls for 2.3 grams of gypsum
to add, I don't bother with acid malt because it's just another variable and 88% lactic acid is much easier to keep around since a tiny little bottle lasts and lasts and does not go stale while acid malt is bulky, and will eventually go stale. but that's just me.