Rules questions: Assault Cannons, Condition Monitors, etc. Options

[Quake]

Hey there, I have a few SR5 questions:

• 1. Can you use a Krime Cannon or Panther Assault Cannon if you're an Ork with a Strength score of only 5 ? I mean: without a weapon mount, tripod or gyromount. Just "two-handed", like you would an Assault Rifle. There seems to be no rule against it, despite MMGs and LMGs requiring Str 8+ and 10+ respectively.
• 2. Besides taking a mount, is there any difference between adding an external versus internal smartgun to a weapon? It seems you would never, ever get an internal smartgun on a Krime Cannon for 22F avail. and +21K nuyen... The external version seems much more worthwhile (since most mounts on an assault cannon will be empty anyway).
• 3. When you get the Bone Lacing or Bone Density Augmentation, do you count the additional "body for the purpose of damage resistance" as counting for the calculation of the Physical Condition Monitor track? Until I re-read the ware's descriptions, that's what I did, but now I'm doubting its legal, even if it sounds "legitimate". If it only increases damage resistance, why not call it "armor" or just "damage resistance dice" instead of the confusing "body term" that you don't know if it stacks or not, is capped at +4 bonus or not, and stuff...

Also, this is more of a YMMV question: why wouldn't people be using Assault Cannons more? 16-17P damage, -6 AP, extremely long range. In SR4A ACs weren't that much more powerful than ARs, except for the Ares Thunderstruck Gauss Rifle for it's AWESOME AP score and high rate of fire. The Panther XXL was single shot, a complex action, and you could get more damage out of Full Auto Bursts at +9 DV than with ACs, without having to deal with the police/military backlash of owning an AC.