Oh I agree with most of the OP's points. Here is my input:

01) Battery gauge is just a glorified cooldown meter. It always fills in a similar pace. They should get rid of it and make the Queen a cooldown itself, OR - for a better solution - Have more abilities interacting with that gauge. Here are some ideas:
a) A "Stun Gun" that brings a stun utility and eats up to 50 battery gauge for a larger duration.
b) Like I've seen in other threads, a "Defibrilator" rez that works at 50 gauge
c) "Bishop Turret" that can be deployed using the same gauge mechanics as the Queen - And it is a healing bot. This would bring a little more (non vital) utility to MCH kit

02) I'd propose to have ammo back. 6 rounds. They are the resource used in the OGCD abilities Gauss B. and Ricochet, so you can choose which one you'll be using as your OGCD. Feels weird to weave in an AoE OGCD amidst your ST rotation and sometimes it can even draw unwanted attention to you.

03) IMO they nailed it with the whole fantasy around the job. Now it really feels like a proper Machinist/Engineer with many skills themed around Edgar from FF6... But the job still has a gunner aspect to it, mainly to its rotational ABC skills and that's fine, but I think the animations there are a little too over the top. I really miss the basic version of the shots. The flashiness could be saved for everything else. Also one nitpick regarding that:
a) Spread Shot always felt a bit awkward to me, animation wise... It's a machine gun thing, but it doesn't really match the weapon. I'd love if it actually used its own weapon like Auto crossbow does. Same thing for Flamethrower.

04) Flamethrower, honestly, what's up with this ability? It's one of the best looking and satisfying to use but virtually useless! I think they should improve the potency and the increase the cooldown to balance it. And also, let your character at least turn when channeling it, to make it a little less clunky to use. Also here's the idea of giving FT its own weapon.