To make money as terran, I`d suggest Agriculture instead of commercial, and also strip mining when you still don`t have a lot of money. To know more about strip mining and how to proceed after that, PM me and I will write it detailedly.
About stacking. First, to win battles you need a wide variety of ships, so go and research everything on your Technology tree, but the capsule lab and the overmind project, those you will only need later. Now you will have all terran and neutral ships and can start battling.
In reallity, you will only battle good once you practically memorize all the races main ships and their weaknesses, and that is only acquired with experience. Also the ability to foresee the opponent`s fleet usually decides a battle, like to guess a Viral player got Borrelly on his front stack.
I will give some general hints as which ships each race usually have, and which ships a terran needs to beat them.
Viral: nowadays, many virals spam V.borrelly, awesome ship with high range but weak to missile, so use your`s terran P.thor on aggressive mode to beat it.
Guardian: ships why very high hull but not so good range, around 6, their main ships are Ruby, Tourm~ and K.hun-li. Use your`s terran Tyr to beat tourm and hun-li, and your`s Hercules to beat Ruby.
Miners: many of the spam their ship M.flysch, very balanced ship, you should use your`s P.thor against it. Most of the miner`s ships are weak to missile.
Collective: they got two good ships they use a lot, the R.sloop and the H.galleon. Hercules completely wipes Galleon, and Garuda should beat Sloop. The only problem here is that Sloop and Galleon got opposing shields, still collectives are not much of a threat.
Marauders: I like to fight them because they got good ships. D.angel, Pyth and Tiger die to Strafez Queen on aggressive. Though Pike can be a problem if it meets your Queens >:) it usually messes up my battles and I can`t think of a perfect ship to wipe it, lol.