You are doing the Lord's work my friend. Out of interest did you choose those positions yourself or just auto-deploy? Also to reiterate the assault guns not being tanks point, the STUGs in game are the F/8 model, which lacks an MG. They really have no business getting involved in the nasty end of assaults.
That was an auto-deploy. I usually place armour reverse slop initially and let the infantry be the eyes on the battlefield, especially as the Germans are supposed to be on defence. Graviteam encourage active defence - ie patrols and ambush opportunities. If you stay in the "Alamo" you will be smashed by their Forward Observors. Yeah, very easy to be tempted to use the Stugs incorrectly - like I did! Need to work with infantry support not independently.
Like all good games these factors do not have one rule for all, it is a case by case basis. Do you want troops to leave trenches? Is it safe to lay wire? I would suggest get to know what the Maneuver Control tool does. Get a pdf of the manual and search (ctl+f) for maneuver. It has a bearing on many issues.