Yes, you'll different lengths when you scroll through Home Depot's furniture leg options.
We used ours on a foot stool, which is filled with books and weighes approximately 25 lbs. No issues with moving it around.
I think you can use the plate but I bought 4 T-nuts for $1 and they worked fine
Yes, by virtue of the screw on the top the overall height can be adjusted maybe a 1/4" or so.
yes, but you will probably need six if it will hold a lot of weight. I use 6 on a custom sofa sleeper we built with 2 twin beds.
yes. I used 6 on a custom sofa bed with 2 twin beds.
This item measures 1.5 x 3.5 x 1.5 inches.
Yes. I used them on a nightstand as well as a small bookcase to achieve a "mid-century modern" look.
yes.
HI, 007JAYC The diameter at the top and bottom of the wooden leg is: 1.5 (1-1/2) tapering down to 0.875 (7/8)