2 inch sounds a little big for a pump that size. The 2 4700 gph pumps I have are both 1.5.
A 2in bulkhead isn't that much bigger than a 1.5..... But I think you could probobly use 1.5 without losing much GPH.
Sockmounts....... Yup, Menards. Get a sheet of 1/4 in acrylic and cut 4 holes in it.... Bam sock mount. Use some 3/4 in pvc with threaded ends for legs. Cut holes in the sock mount plate and run the threaded PVC through them. That or glue strips to the sump walls to set the tray on. Or don't cut the tray except for the sock mount holes and build a little stand out of pvc to set the sock plate on.
Just keep in mind it HAS to be fairly simple to change the socks or it starts becoming dreadedly UN fun. Either the sock tray or the drain tubes will have to move. If the drains are stationary make the tray removable. If the tubes can come off then you could make the tray permenent. I brainstewed over this lil obstacle for many weeks. I ended up opting for securing the drain tubes permenently to a settling chamber then just put 4 bulkheads in the chamber wall dumping out into 4 socks. That way I could avoid trying to split the drains from 2-4 to hit all the socks. Got rid of alot of plumming, allowed everything to be permenent since the socks didn't have to be directly under the drains, making changing them really simple. PLUS if the settling chamber works right most of the heavy craap will sit in the chamber till a bottom drain valve is flipped.... NEVER even touching the filter socks.
Another option would be to cut slits or holes in 4 in pvc and glue to the bottom of sump. Mount socks in the tubes.