100 Swedish crowns (1 "krona", several "kronor") is worth about 11 Euro, or 7 Pounds or $US 13.50.
Check Forex for up-to-date exchange rates. They are often better than the banks.
There are four airports within range of Stockholm.
Arlanda is the main airport, the major airlines fly there. You can get from Arlanda to Stockholm Central by
Bromma Airport is used mainly for domestic flights. There's a flygbuss (20 minutes, 70 SEK) and also normal public transport, e.g. you can take bus 152 to the station and then the commuter train to Älvsjö.
Skavsta and Västerås are two "budget" airports used by Ryanair, e.g. there are several flights to and from London (Stansted/Luton) every day. Take the Flygbuss to town, it's the only sensible option. They leave whenever a flight arrives.
The nearest hotel is Hotell Älvsjö, and the Erlang Users Conference has some pre-booked rooms available at a somewhat lower conference rate, if you tell them you're going to the conference.
Many hotels are booked up due to some Technical Exhibition but this might be a good (cheap) choice Hotel Formule1.
There are many more choices in town, ranging from luxury hotels down to hostels.
Stockholm is not a good place to get around by car.
Public transport is excellent, though not cheap. There's a great webpage with timetables, maps and information. The buses, trains and subway all use the same tickets, some of the options are:
You might also check the Journey Planner or the Tourist Information. (Tip: the dots above the letters in station names such as Älvsjö are crucial, the trip planner won't give you the right stations if you leave them out, but it does, eventually, give you some buttons you can click to get those letters if your keyboard doesn't have them. Alternatively, cut and paste the name from this page.)
To get from Central station to Älvsjö, find the commuter train "Pendeltåg". All southbound pendeltåg lines stop at Älvsjö. Central station is a bit of a maze, if you manage to get from the flygbuss to the Pendeltåg in under five minutes, you're doing well!
We are inviting EUC participants arriving the day before the conference to a sight-seeing trip around Stockholm and a beer together at a pub.