Yes, yes and yes. Unfortunately, conceptual issues are harder to deal with than editorial. The idea of cutting Sidious altogether is a good - that way his appearances in the PT will mirror those in the OT (i.e. none/a bit/a lot). However, preserving the surprise is a moot point, since everyone already knows. Even people who don't know who Ian McDiarmid is and missed that the OT Emperor's name is Palpatine can recognize the TPM Palpatine as the OT Emperor. Nevertheless, go ahead, it's a good idea and I'm sure a lot of fans would love to see it.
good points