Hi Christian, most of this information is found on the Need to Know or Route pages.
The Fjord Norway page is here: http://www.cyclenorway.com/routes/norse-all-road-series/overview/fjord-norway/fjord-norway/

a) The prevailing winds are south-easterly, meaning, in general, there is more tailwind heading north.
But you’re going through the mountains that will sometimes shelter the wind.

b) I don’t think anyone can answer that question. Maybe the Strava heatmap can give you a clue about which way cyclists go? But as far as I’m aware, there is no preferred direction.

C) If you had two different routes, we could compare which is more flexible. But the Fjord Norway route is pretty straightforward, with little opportunity to deviate.

D) All the mountain passes are clear of snow by mid-June. The only one to double-check is Gamle Strynefjellsvegen, which usually opens on the 15th of June.
http://www.cyclenorway.com/opening-closure-of-roads/

In either direction, you will get both tough and easier sides of the mountains to climb. There is not much difference in either direction. If you go North-South, there is 14100m and South North 14500m. Four hundred meters over 800km is very little difference.

If you go over Aurlandsfjellet to Lærdal, you can take the bus through the two long tunnels to Sogndal (or vice versa). I think there are two a day, and if you time it right, it should be a simple procedure.

If I was you, I would start in Oppdal and end at the famous Flåm microbrewery, drinking their famous IPA! That’s a good way to celebrate your achievements! You can also go up to Myrdal and take a train to Opsete and continue riding to Bergen if you want to extend the trip. See the Oslo to Bergen route.

You will highly unlikely come across a bear on your travels in the North. Bears in northern Scandinavia are located in remote areas away from roads and towns.

Brown bears are, by their nature, fairly shy creatures. They are not aggressive by nature and will stay away from humans and keep to themselves where possible. The females tend to stay within small geographical areas, but the males will roam over much wider distances.

I would ensure food is not left out, but that goes for any time you wild camp, as mice and other creatures will take the opportunity if it prevents itself. You don’t need a spray or anything like that. You’re not going hiking in remote areas, are you? Sticking to roads is never an issue with bears in Scandinavia.

Thanks. As we are not decided yet where and when to go: what would be your advice to get ghe most out of Norway in 7 weeks? Budget: midrange rooms, 70-140 km per day cycling in ok-good weather (or up to 2500 m climbing / day), maybe 2 days per week for sightseeing/ muscle relaxation;) and some flexibility in booking rooms? To be honest, i’d like to consider also Lofoten but i dont want to decide today when I will reach it…
Is the train Oslo-Trondheim running again (including bike transport)? If yes, we may take the train up to Bodo and start in Lofoten and then venture down south…

It all depends on where you are cycling. Usually Early to mid-June, the season hasn’t fully kicked in yet, so hotel rooms should be available without too much notice. In July it might be hard to find accomodation without a few days notice. Especially in top tourist destination areas. In places like Lofoten usually you will need to book many weeks in advance. In addition, it’s also based on how much you’re willing to pay. Usually, high-end rooms are available last minute, but budget rooms will be booked up days, perhaps weeks, in advance (Lofoeten months in advance).