As regards your tactical question. If you want to get better read, the Art of War for a start, read Caesar's Commentaries, read Polybius. Read all those guys.

What you'll rapidly realise is that every battle between relatively matched forces works on the same principles. A Line on infantry with cavalry on the flanks, an infantry and cavalry reserve and skirmishers to soften them up.

Your infantry should be in a single line, your whole army needs to stay together and you have to stop yourself from getting out-flanked, thats what cavalry is for. Aside from that you just need to learn to control your army and learn the proper uses and tactics for different unit types.

Find a way of fighting that suits you, then fight everyone else on your terms.