Believe it or not, the controls are as good as they get for a touchscreen! Only bad thing is you can't scroll "natively" with touch (like in a website, or google maps), you need to drag your finger to move your mouse to the edge of the screen.
They work like this:
LEFT-CLICK MODE:
Tap: Left click
Long tap then move finger: Long left click (for selection boxes)
RIGHT-CLICK MODE:
Tap: Right click
Long tap then move finger: Move cursor without clicking
Swiping left/right/up/down then holding scrolls the map, and you can toggle shift and press hotkeys (cannot be customized, so you will have to change the in-game hotkeys)
They seem hard at first, but aren't too hard to get used to. When I have some minutes to spare, I play a skirmish or two. Shame it takes around 2 minutes to get into one...