Here is the response I received for the same question from fylkesbaatane@fjord1.no on 29 April for 30 June the same ferry change we plan to take:
"You can take a boat depart Balestrand at 11:55, change for a ferry at 12:45 in "Midtfjords' for a ferry, and arrival time in Gudvangen is 14:30.
The price for 1 adult is NOK 221, and for 1 senior, NOK 134.
We have no speedboat to Gudvangen (from Balestrand). There is a boat from Flam to Gudvangen that takes about 2 hours. If you get to Flam with the express boat, you will arrive in Flam at 13:25, then the boat dpts Flam at 15:10 arrival in Gudvangen 17:20.
The bus (from Gudvangen to Voss) is not our business so please check http://ww.skyss.no/Global/Bussruter/Hardanger_Voss%2001052010/900-950_Ama_Voss.pdf.
You can purchase tickets when you arrive, paying either in kroner or credit card."
Lise Ekevold was the Fjord1 person who responded. She was very prompt and helpful. This is supposed to be a very beautiful trip! Good luck!