Sling, both the guns on the arado facing backwards were movable. They were aimed by remote by the gunner sitting in the back of teh cockpit facing backwards. The guns (have teh exact numbers in a book), if I remember correct, could be aimed 30 degrees down, 60 or 70 degrees up and 60 degrees out from the fuselage. I have film fotage (on tape not computer) of it aswell when you get to see both the guns move and the, exteremly big comlicated, remote aiming divice.
Pyro, HT, please add it now. It did have it in real life. If it can't be done, please give us the single 20mm gondola option.