You know, an Evo Falcon with Gattling Guns on it would rock.

...

I wonder where I got that idea from?

I think you're thinking that the SeaDoo is the only vehicle with Body 5. Look, just use literally any vehicle. All vehicles are drone-able, with trivial effort.

Is that from recoil?

Yes...

Not what I am saying, I just am thinking the idea of a semi torpedo shaped minigun toting 4 track driven monster would be cool.

By the way I am reading it You can use the esoteric (APDS, AT ect) ammos for a gauss rifle?

As far as I know, gauss rifle use a very specific ammunition.

They use special Assault Cannon ammo, 'Gauss Rifle Rounds'.

Also, I'm concerned about a game of Shadowrun that requires answering questions about extra-huge custom drones, drone recoil, custom gauss ammo…

Nope, Gauss rifle only fires gauss rifle ammo, that should be pretty obvious.

We are helping the Royal Family of Nepal repel SK, takes some hefty hardware to fight the chummers off.

Bah, just go with the old fashioned explosives technique, and remember, "P for Plenty!"