Very comprehensive review and build description.
One thing, though, in Step 7: The fender modification that DML shows as an optional step, where the angled front fender ends are cut off and replaced with parts K34(K35) should NOT be followed for a late (or even standard) production StuG IV.
The curved front fender sections are only seen on the first 30 PzIV chassis diverted from Nibelungenwerke to Krupp-Grusonwerk in December '43 for the intial StuG IV prodution (completed by early Jan '44).
All of the remainder of the StuG IV production at Krupp-Grusonwerk utilzed the kit's molded angled front fender ends.
So, on the late StuG IV, save yourself some work and don't follow the DML optional sub-step. DML should have left this out of the late StuG IV instructions, but, hey, it's DML with all the instruction issues that means.
If you're buildng the DML early StuG IV, only use the optional K34(K35) parts for an intial production vehicle. Also use optional part K25, rear hull, Step 1, square aux engine exhaust hole cover, but cut the bolts off and add a weld bead around it. Also, add zimmerit for one of these intial 30 StuG IV's. There are also several other optional parts that are different, like some of the tool choices.
At any rate, nice review and build!