You will find a lot of good parking-spaces around the cathedral and parking is restricted there to 5 hours between 08.00am and 05.00pm. That way it is also possible to stay with your small motorhome there overnight without extra-fees.
The parking-fees are increasing like :
1 st hour of parking is 20 NOK
for the next 20 NOK you get only 52 min of parking and so on untill you finally pay a total of 110 NOK for 4 hours of parking.
and for the last hour you pay already 40 NOK, so maybe you come back after 4 hours and pay again. You will need coins for the machines that are placed somewhere on the sidewalk and put the receipt behind the windscreen.
Transportation inside of Norway is a bit tricky and the trainsystem has only a few connections between big cities.
I had to take the BUS from Trondheim to Bergen, that distance is about 700 km, and the comfortable bus left Trondheim at 08.00pm and you arrive the other morning at 09.45 in Bergen. There will be many stops for 10 and even more minutes at cafes, petrol-stations ect. along the way, where you can eat or drink something and in the morning you will take a ferry, that also has a restaurant onboard.
I was lucky to have the total last row for myself to sleep on and most of the time there were only 8 or 10 other people on that bus.
The ticket was 560 NOK (=64 euros), that is about half of the price for the ordinary train Trondheim-Oslo-Bergen (= 1050 NOK) that is leaving at around 8.25 am and you arrive in Bergen late at night. A sleeping-compartment for the nightrain would be 850 NOK extra (=100 euros)
The central bus-station is next to the central trainstation, buy tickets at the counter or the busdriver, big lockers (I had 1 suitecase + 2 rucksacks and it was big enough) for your luggage are available for 50 NOK and you need coins for them.
There is also a selfservice restaurant in the station, they serve breakfastbuffet for 89 NOK from 07.00 - 09.00 am.
Toilets will cost 10 NOK and you need a coin !
Trondheim was our southern place in this Nordic trip.
From there we cut through the mountain on a beautiful
Road across the border to Sweden.