-how fast does the player IS turret move???
It doesn't seem to be moving that fast, really. It is twitchy fore sure, and that's ArmA2's mouse controlled turrets for you. Using a joystick or pad makes things a lot smoother in ArmA2, so I expect the same is true in Iron Front.
-good to see the German tanks drove around presenting their flanks nicely (bad AI or dozy humans?) and skylining themselves beautifully
The tanks were mostly Tiger IIs from Schwere Panzer-Abteilung 501. This unit seems to have had an unfortunate record of being battered in the flanks during the Lvov–Sandomierz Offensive, so dozy humans (or bad AI) are not necessarily something that one only finds in games! Also, the narrator for the video states that he had 'placed' some tanks down, so no doubt he is fiddling with the editor, which also means that the path taken by the panzers was his responsibility, up until the guns started firing. More careful scenario design could limit these situations, although they will (rightly) still happen on occasion in both SP and MP games.
-If you hit a Panzer IV in the side, does it normally flip over? All 25 tonnes of it?
That was rather crazy, wasn't it? One suspects that this was a result of the new complex damage system, with destroyable parts, ammunition explosions, etc. etc. causing an anomaly like that. Hopefully it will be a somewhat rare sight.
-not sure on that external birdseye view that seems selectable...would seem to be rather gamey
As it is a game, one would be surprised if Iron Front wasn't
rather gamey. As someone who has spent almost all of his ArmA2 time creating and playing high command scenarios, I find that external views like that are actually pretty handy, and I am glad that they are in. If one does not wish to see them, one does not need to use them, and, if ArmA2 is any guide, MP games can have the view disabled at the server.