I would provide all PA and sound equipment large enough to accommodate your reception/party.
My set-list includes, Jason Mraz, Bob Marley,Jimmy Buffett, Ed Sheeran,Bill Withers, Izzy Kamoni, John Mayer,Marvin Gaye, Sting, Peter Gabriel, ETC.
1. When I perform as a single act, I use a looper effect pedal. This allows me to add drum effects, backing vocals and lead guitar. I have done numerous weddings in this fashion with more than stellar responses from clients.
2. As a duo I would incorporate all of the previously mentioned features above with the addition of a second guitarist.
3. As a 3PC band, drums, bass guitar and lead guitar. There are no loops, just 3 professional musicians performing as you requested.
If you have any questions please feel free to contact me directly.