I used spiral duct at my shop. It was pricey but I like it. I also like how easily reusable it is (the duct and the fittings).
I started off with my dust collector mounted on Oneida's stand. I had a couple of wedge shaped wood strips under the legs to account for the downward slope of my shop (which is a 2 car garage). Kept it like that a few years then wall mounted (with Oneida's wall mount bracket) it to gain some height and eliminate a couple of 90 degree elbows in the ducting system.
I used 4 casters. I'd say about a 2" caster. I bought them from Home Depot. Yes I did just drill the bottom of the drum for machine screws, nuts, lock washers to mount them. I used clear silicone caulk to seal up the holes.
I don't know that it's really necessary but I like it ok with the castors on the drum.
Good luck with it.