Questions re SU Mechanics

[redboot]

I have a few questions about SU units for the more experienced.

1. If I manually assign a SU to a combat unit, will it stay with that unit forever unless I manually put it back in the HQ? Will the program ever relocate it to HQ automatically? Is the answer different for pioneer/sapper SUs?

2. Why is it when I click on the assign button in the unit detail and see what's available for manual assignment, those unit types do no necessarily appear in the attached SU list for that unit's HQ. For example, I can assign a Flame Tank Battalion to the 12th Panzer Division, LVII Crops, but no such unit appears in the LVII corps attached unit list. Is it sitting a command level up?

3. Why does the software make fewer SUs of a specific type available to a unit than are in that HQ. For example, I might have 1 pioneer battalion available for that same 12th Panzer division, but the LVII corps HQ says there are two in the HQ. Is that just a program allocation algorhythm?

4. What is the main benefit of medium tank SU sttachments? Would I tend to attach them to infantry units for an "effective" combined arms bonus? (Same question for Flame Tanks.)

5. When does the program actually decide whether to devote SUs to a combat unit/attack? (Leaving aside artillery.) I.e. do SUs like STuGs and Medium Tanks REQUIRE manual attachment or will the program seek to allocate them to an attack at some point during the action phase?

Obviously, I'm trying to get the system clear in my head and I would appreciate any insight.