No buses are fully included. There's one bus line for which you can get 50% reduction, see the Norway page under "Domestic trains” (so you don’t need to use a travel day for this bus).

Where you can buy tickets depends on the bus company.

thanks! I don’t have problems with the travel day because i have the 2 months pass, is the same thing?

Then you don't need to worry about travel days indeed :)

I had the 3-month pass myself last summer :)

but the bus is not included if i have the 2 months too right? is always at 50% ?

It's always 50% for the bus line mentioned on the Norway page. For other buses, you'll have to pay the regular fare.

This bus is the ´missing ´link´ between the end of the line north and the small strecth to Narvik fanning out from SE=Sweden.

NO is fairly pricey for any form of transit. But actually some 80-90% of the usual 1st time touristy sites are reachable by train and I suppose you will not want to visit the full 100%, so just select with brains!

It is however true that between some cities along coast going by train forces you to go far inland-often back to Oslo, and then next leg. F.e. Stavanger-Bergen. Use SHIP in between.

On the site of entur you can check about any domestic connection by whatever means of transit there is