Hi there, looks like a great set of plans.
I had a thought about the lift location, when I view the Roof.pdf it shows the thickened pads for the lift not aligned with any of the overhead doors (if I interpret this correctly). That seems like it would be a pain down the road to try to pull in and make a turn and crab back and forth to get aligned. Maybe those pads didn't transfer over from another detail where they are in a different location and honestly I didn't back-check it...
Also I would advise an under-ceiling to the open area. Keep birds and critters out of there will save a lot of problems. Either some kind of mesh-netting or a solid ceiling...could be a similar metal panel as the roof.
I built my own floor to handle machine shop equipment up to around 10k, plus forklifts that move it around basically double that load on the front tires. I poured a 6" thick slab, 4000 psi, base was 6" of 3/4" nominal crushed limestone, plate-compacted. Rebar 16" on center in both directions. Sealed with a curing sealer to preserve hydration and maximize strength, saw cut in 10-12' squares the next morning after the pour. Has been flawless thus far.
If you didn't have those loads then a 4" minimum slab would be very acceptable in my thinking, of course the thickened pads for the lift. I wouldn't hesitate to make those pads 3 feet square. The extra area improves the moment-bearing on the soil below.
I didn't really see any windows in your shop, I would recommend them....the natural daylight is awesome lighting and free

. I recognize it can present a solar-gain issue and/or entry issue, but placing them up-high would solve at least the forced entry issue. I also think it makes the shop look better, more like something that matches a house...I'm purely guessing here but the level of detail says you're building close to a residence.