(3) bus from Gudvagen to Bergen?
Welcome to Fodor's. You can not book the Flamsbana ( Flam Railway). You can purchase tickets at most rail stations including Oslo Central. Please note that you can not get tickets at the Myrdal Station.
For the ferry trip from Flam to Gudvangen go to www.fjord1.no for booking and further information.
I'm not sure about the bus from Gudvangen as usually people take it to Voss then train to Bergen. If actually planning on taking the bus through to Bergen, have a look at bus routes on the fjord1 site. I don't think it's necessary to book, just buy tickets on the bus, but do double check especially time schedule and connections.
Norway in a nutshell - Most beautiful scenery in Norway.
Buy it as part of the Norway in a Nutshell package - all segments - can buy locally from various stations involved.
Yes, Norway in a Nutshell is a possibility, but there really is no reason to use them when you can easily do it yourself.They are simply ticket facilitators. You are covering the same territory as NiN. And, if using the train ( possibily from Voss to Bergen) you can take advantage of the minipris ( advance ticket prices) which are considerably cheaper than those offered by NiN. Since you have already purchased your tickets for train from Oslo to Myrdal and Bergen to Oslo,and you can't book the Flam Railway ( get your tickets at Oslo Central Station) or the bus for that matter, your only booking will be with Fjord1.