ABS (solvent (aka "glue") can only be used to join ABS pipe to ABS fittings. (The same rule applies to PVC solvent) Your drain fitting should have directions for installation enclosed. The shower stall rests all of its weight on the floor, usually with mortar spotted beneath to prevent sagging or flexing under heavy weight, and is nailed or screwed to the studs at the top and down the edges to keep it from shifting. The drain does not support any weight. The pipe needs to be cut to the correct height as will be indicated in the drain fitting instructions. Follow the instructions carefully and you shouldn't have a problem.