Firing with a tank

If I give a Churchill tank an order to fire , do I choose a single weapon to fire with?
The Churchill has two machine guns and a main gun , but I just choose one gun to fire at a single target?

Choose a weapon type, choose a target.

Fire all weapons of that type with the target in its fire arc.

Choose a mode of fir (suppressing or aimed) and weapons system (main gun HE or AP, or MGs) and a target.

So, perhaps Suppressing fire with MGs at an infantry squad. Or Aimed fire with HE at an anti-tank gun, or aimed fire with AP at another tanks. All combinations are allowed, some aren't that useful though, but you can fire, for example, AP for suppressing fire at infantry, it just doesn't do anything (in game terms)!

If I fire both of my tank's MGs in Area Fire against infantry, do I make one roll at ROF6 or two rolls at ROF3?

ROF 6