I'm having trouble remembering but I think many shops were closed on Sunday. The cable car runs every day from 10am-6pm. It cost 10euro for single trip and 14.50euro return.
Funchal is lovely to walk around just make sure you have comfy shoes.
We were there on a Sunday this year. There were a few shops open. Most of the restaurants along the waterfront were open. The cable car was going, just remember that there will be church services in the church at Monte. I don't know about the hoho bus, but most of the tourist attractions go all week.