This computer haven't got Latvian letters - so this time in English:
1, For coming here for the first time I recommend ferry (Riga-Stockholm) and then bus, which U order together with ferry ticket. So, U can take all staff needed. Doesn't matter how much it weights and is also very cheap ~ 30 LVL. But it takes lot of time - all night on ferry and then 5 hours in bus. But bus is very nice - couse it takes U straight from ferry in Stockholm to Karlstad and only costs 11 LVL!!!.
2, And if U want to some time visit home and U don't have time to waist on boring boat - I recommend Rayanair.com :D with hand luggage. Going from Stockholm Skavsta to Riga. Flight takes ~ 50 min. After U have plane tickets go to this site www.sj.se - there U can order matching train tickets. Going from Karlstad C to Skavsta Flygplats. If U buy tickets in last moment, they probably will be more expensive. Anyway for train tickets for both ways U will pay ~ 300 - 400 SEK, which is 20 - 28 LVL.
3, Train ticket goes only up...not like with special offers from plain company
4, It is good to know: that this airport is really small and boring. Train tickets U ordered wouldn't go straight to airport - U probably will have to take 1 or 2 trains and 2 buses. It depends. but U have schedule which is very accurate, so there shouldn't be any problems. Even heavy drunk people for the first time traveled successfully.
5, If order tickets 2 months advance journey will cost U ~35 LVL.
1 month - could be lucky and the same/ ~60 LVL
1 week - ~could be lucky and bit more, but usually 100 LVL
6, Ferry + bus TICKET ~ 30-35 LVL
7, If You take plane - You will have breakfast in Latvia. Plane departures at 10:30 and arrives at 10:35 :D. It means you have beaten the time. At 17:00 U be in your dorms in Karlstad.
8, Oslo is even closer to Karlstad than Stockholm - so maybe U can try that way and see also Oslo. But train tickets from there is even more expensive, but maybe it is worth it to see another beautiful and expensive place.
I really hope this information was useful. Hope, that someone read it.