I deal with a lot of sound, and I have found these 3 books to be invaluable:

Dialogue Editing For Motion Pictures - John Purcell

Practical Art Of Motion Picture Sound - David Yewdall

Sound Effects Bible - Ric Viers

if u can edit the song down to the specific sections needed for each location that could work...but its easier to just record the whole song...also easier when it comes time to sync/edit. Some advice..get as much, if not more, B-Roll than performances...B-roll makes music videos

Slightly better version here:
https://www.youtube.com/watch?v=Gy5kDukQkZA

Not very realistic if the slide on the pistol doesnt move when firing a shot. Saw an example done by Red Giant where they masked and animated it to move...way more realistic that way.

the cost of "a combination of handheld, dollies, jibs, cranes, drones, tripods, monopods, bungie cords, wires in general, steadycams..." vs. the cost a gimbal...hmmm....doesnt take a genius. Gimbals are everywhere and many people buying them have no filmmaking experience. Clearly the video is geared towards beginners so to speak...but it also highlights the versatility of this relatively inexpensive purchase by being able to achieve shots that would normally take a van load of equipment to pull off (as you pointed out).

Video/Sound Devices makes top notch gear. I've had the Pix-E5 on my short list ever since it was announced...this just makes me want to get my hands on one even sooner.