Your concept seems to add up nicely. When doing micro management in small steps, you need to remember that this way you cannot let a player control many units at the same time.
What sunandshadow suggested was a 1:1 relation of movement squares and action points. Units have each a different amount of action points, which represents their agility. Attacks all differ in cost. (PoxNora)
You dont need to have multiple actions for multiple attacks, btw. In Battle for Wesnoth a unit hits several times in one attack, (rolling for each attack separately).
Also, i want to point out that combat roles imho are.. a lot of fun. It is important that you have unit types specialized for certain tasks (classes), which the players can easily identify from the visuals. It adds flavor and tactical depth. Id research a little in that area.
PS: i hope i do not appear to be mansplaining, im actually an amateur, too