We do them all the time - they are fast and a lot of fun.  We usually have five rehearsals: One read through, two acting, one Tech and one Dress.  Remember it is all about how it sounds - very different.  These shows are technically complex:  EVERYTHING needs to be miked.  We use 8 to 10 mikes as a minimum.  You need a good sound man to ride the levels. 

We usually have three people on the live SFX - one on the sound table making incidental sound (silverware during meals, pouring water, etc), One on the large SFX (doors open/close, phone ringing, pickup/hang upup/dialing) and one on the walking boards (usually one for hard surfaces and one for gravel). 

We have two people on the recorded effects (usually two Minidisks and two CD players) plus the mixing.  We have recently moved to computerized sound cues.

Plan on spending a day on recording sound effects where you can't find just the right pre-recorded cue.

Music is EXTREMELY important, stings, bridges, theme music add much to the play.  We have some very good people who compose the music for each show - use a high quality keyboard with a lot of voices.  We have done some with live music (always preferred) and some where we recorded the music before hand.

You need one mike for each actor that needs to be there at the same time - usually four of five - plus one for the announcer.

Tech is the hardest rehearsal - if you don't have experienced people you might want to rehearse them seperately.

A Couple of hints:  Only one actor has focus (for sound purposes) at a time.  If that person "walks away" from the others, it is the others who have to move away from their mikes.  It gets confusing if focus changes often or rapidly.

The actors need to exaggerate the effort to do things like lifting a heavy object.  Since it is all in their voice, they need to let the listening audience know how heavy it is or how out of breath they are.  The actors all want to do their own sound effects but let the SFX people do it.

Try to use identical mikes for the actors.  A Shure may sound like a Sennheiser, but they come out very differently to the audience.  They react differently to the distance from the actor to mike (for "off mike").  An actor often uses different mikes during a show (maybe the mike he usually uses is in use by another actor) and he may sound  very differently on different mikes.

It is a lot of fun and we have tons of volunteers to do the SFX.  Our audiences love them. 

Hope this helps.