Been using Sheila Shine on my 32x120x1/4in steel plate bench top and once dry it’s invisible and prevents rust.
Super easy to apply, just wipe it on and let dry.
I used dense packed cellulose on my shop walls with netting tightly stapled to walls. Then vapor barrier.
Keeping cavities to 2 -3 ft high will reduce settling.
Happy with results, and yes you’ll need a more powerful blower than the ones you rent at HD and such.
Here, 2in XPS under slab and 4in XPS in vertical perimeter plus 2x8 ft XPS 2in skirt outside perimeter except corners where 4x8 ft XPS 2in is used.
Works great so far.
Not an expert, just a thought.
I would pipe waste from the garage to a sump basin sized large enough to pump cycle waste and fill the entire 3in pipe and them some additional gallons so solids don’t dry up and block pipe.
Mine is 200ft with 2in pipe and sump basin is 84 gallon inside heated...
Mcmaster Carr has 10ft of motor shielded cable if you go that route. That's what I used for my lathe and mill just 2 weeks ago. Also shielded 18g control cables.
Good luck with your install.
I’ve done dense pack in my barn walls and loose for ceiling. Very effective insulation.
You need a good stapler, netting and a better blower than what’s available at HD.
The netting is stapled 1/4 in inside the studs and partitions to avoid having cellulose trapped on the studs. Gluing it seems...
I did mine surface mount. 90 degress to the trusses. More surface to screw the metal panels on, specially if you pre-drill panels. 1.5 in vs. 3.5 in.
Does not take much to miss a truss.
Plus as already said, much faster to install.