Questions about transmission

How difficult is removing an automatic transmission (90 LS) and how much time would it take a reasonably skilled person? That is with a repair manual to help. Also is it generally better to rebuild a transmission or just get a new one entirely.

The shop next door to my company rebuilds transmissions. The tools required to rebuild an automatic transmission is the difficult part. You’re better off getting a known good working used unit or a rebuilt/remanufactured transmission.