Unless you're after records that can't be accessed on the Internet, such as court records or estate inventories (bouppteckning), do contact the local historic societies instead of looking at records you can just as well - and probably more comfortably - look at from home (you will not be allowed to see original records, only copies and microcards).
It's a good idea to contact the societies in plenty of time before arrival, so they can prepare and locate materials for you and organize showing the local museum with someone who speaks English.
Hässleby local historic society:
Mariannelunds och Hässleby Hembygdsförening
Chairman: Tomas Braag, Ubbekulla 2, SE-570 30 Mariannelund, Sweden (write a snail-mail letter)
The site is unfortunately only in Swedish, but there are plenty of pictures.
Södra Vi local historic society:
Södra Vi Hembygdsförening
Chairman: Jan Svärd, Flädervägen 15, SE-590 80 Södra Vi, Sweden (again, snail-mail letter is best)
Again, the site is only in Swedish, but with plenty of pictures.
The local historic societies are immensely knowledgable about where farms, crofts and cottages where located in the old days and what happened to them. They usually have very good archives with old pictures etc. and can also tell you about local customs and history. The local museums are usually lovingly restored old houses with veritable treasure-troves of old artefacts. They will give you a great idea of how your ancestors lived before emigration.
Ingela