Apel

In general very easy, but it depends a bit on where the ship docks.

Of course it's walkable. And it is a very nice walk through some lovely parts of Stockholm. But, it will take around an hour on foot and that might not be how you plan to spend your time. Bus 76 is a good option. Takes you from Frihamnen to Gamla stan in 16 minutes (maybe 18-20 minutes if traffic is bad), you can pay for the bus by tapping a Visa or Mastercard in the bus, or use SL's app. The ferry is also an option as mentioned. A bit slower, but gives you great views of the city from the water. Taxis exist and are usually easy to find, but a small warning: Only use Taxi Stockholm, Taxi Kurir or Sverigetaxi! Avoid other companies, many smaller companies are perfectly fine but there are unfortunately a couple that specialize in scamming tourists.

Unless your licence is follows the EEA, Vienna convention or Geneva convention models, you need an IDL. https://www.vegvesen.no/en/driving-licences/driving-licence-holders/driving-licences-in-norway-and-abroad/using-a-non-eueea-driving-licence-in-norway/?lang=en And make sure you know the road signs and rules of the road, and follow them to the letter. Norwegian traffic tickets are no joke.

Or buy the tickets at www.vy.no, i.e. from the company that actually operates the train.

And it is very easy to combine Gamla stan and the ABBA museum. It's a short ferry ride from Djurgården to Gamla stan.

Probably not. Stadsgården is very central with a lot of things within walking distance.

From Frihamnen I'd suggest you just take the bus. The regular bus that is, not the hop on hop off. Take bus 76 from Frihamnen to Djurgårdsbron, from there you can either change to the tram for one stop or just walk the last bit. Apart from the app mentioned above you can also buy single tickets by tapping your credit card (Visa or Mastercard) on the bus.

From Nyhavn, the easiest and fastest way to get to the airport is most likely the metro.

Many tourist traps as well, so checking reviews before is not a bad idea.

Basically, yes. At least you don't have to tip anyone, and people won't be offended or call you names behind your back. Tour guides? No tipping as long as you have paid for the tour. Taxi drivers? No tipping, although you can round up to the nearest 10 kr if paying in cash. Bartenders? For a simple order, like opening a bootle of beer, pouring a glass of wine or making a "simple" drink, no tip. Although if the bartender is giving you a lot of recommendations or you have a very complicated order, a small tip is not a bad idea. Someone who helps you with your luggage? No tip, although I'm struggling to see where I'd find someone helping me with my luggage that isn't a taxi driver or works at a hotel. Waiters? You can leave a small tip (5-10%) if you want, but there is no need to and you can just pay the amount on the bill.

Maybe. Where are you flying to?

If the author of this article is to be trusted I don't think you need to worry about Sweden. https://www.self.com/story/im-a-foodie-with-celiac-disease

Regarding Stockholm, I would not assume there will be any tours available on the spot. Although there will probably be taxis, depending a bit on where you'll actually dock. There are multiple cruise ports in and around Stockholm.

I don't know what the cost of the Hoho bus is, but if you just want to get around the city a day ticket for all public transportation costs €9 and most cruise ports have a tram stop nearby.

If it is medieval music it will most likely not be a string quartet as the string quartet was invented in the classical era. Probably not an orchestra either as the modern orchestra is a much later innovation.

Avoid Rail Europe as mentioned and buy the tickets from DB, www.bahn.de The mentioned departures currently cost €34,90 each if you buy them from DB.

Taxis in Stockholm are good, but expensive. The local public transport system on the other hand is also very good and in comparison rather cheap.