Third person view wil be disabled/unavailable in the final release, unless of course we decide to make it a server side option. Which I doubt. The reason you see it in vids is for debugging and video taking purposes.
As for weapons grouping there are no limitations. This is because of the way weapon grouping works. You can put any weapon in any group so all you have to do to alpha strike is put all your weapons in one group then fire the group (which is a hotkey associated with that group) IE. group one is right click, 2 is left, 3 is middle, etc. Of course these keys can be changed.
This method allows the user to tailor groups so that for example you don't overheat and explode.
Weapons can also be part of multiple groups, so for example you can have a anti-mech group, a anti-elemental group, a all laser group, anti air group, etc etc. Theres a lot of possibilities that can accomodate someones playstyle or particular 'mech.