Ouch, very big questions.
Well, here goes - and I'll be very glad if someone fills in all the things I've missed...
In the late 17th century a new evangelical movement started in Germany, called the Pietist movement. Students (Swedes who were serious about their education always went to German universities) and prisoners of war brought the new religious movement back to Sweden, and by the 1720's it was at its height. The movement used lay meetings, so-called conventicles, to spread the word.
In 1726 a proclamation against conventicles (konventikelplakatet) was issued. This caused the Pietist revival movement - which had hitherto by and large worked within the Swedish Church - to go underground and, of course, become hostile against the Swedish Church. In the wake of the Pietist movement followed the Herrnhutist movement, a similar evangelical movement which was also imported from Germany.
From this background the läsare movement was born. It started in the 1750's, and was re-born in the the first decades of the 19th century. The movement became especially strong in Norrland, which had an old tradition of läsare. It has to be noted that the movement was illegal since they gathered in conventicles.
The proclamation against conventicles was repealed - over the protests of the clergy - only in 1858; the proclamation was replaced by a bylaw (förordning) which was repealed in 1868. However, some of the regulations remained in force until 1951!
It is true that the läsare movement was especially strong in Norrland, but did not go much further south than Västmanland and Uppland. This is due to the fact that in the south and southwest (from Skåne and up into Bohuslän) another religious movement got under way: the Schartaunism. This movement, which kept well within the Swedish Church, was started by Henric Schartau (1757-1825), a clergyman in Lund. In the beginning Schartau was much influenced by the Herrnhutist movement but broke with them and their emotionalism in 1787. Schartaunism is a very dour form of Lutheranism, and it is still alive and kicking in Göteborg and Bohuslän.
In the northern part of Norrland another religious movement was started in 1844: L?stadianism. A clergyman in Karesuando, Lars Levi L?stadius (1800-1861), founded this movement. It has its roots in the Pietist movement, combined with Sami popular tradition. L?stadianism has much in common with Schartuanism in that it is against secular vanity (like having curtains and colourful clothes), but differs from it in that L?stadianism is very emotional. This movement is also still very much alive.
When there was no longer any resistance to the läsare movement, it died out and was eventually replaced by e.g. the Baptists.
Certainly it was not propertied, well-educated urban people that took part in these Evangelical movements. However, poverty and poorly educated are relative terms. In the 18th century Sweden was a poor country, but the general level of education was something that all travellers to this country remarked on: more than 90% of the population was literate (at random, the parish of Skellefteå has been closely studied: in 1724 85% of all adults could read, 98% of the young people were literate); such figures were unheard of in the rest of Europe. The one book you could be certain that almost all households had was the Book of Hymns, which also contained prayers and texts from the Evangelists. Many also owned a Bible and quite a few had in addition collections of sermons. This was of course also why such movements as the läsare became so popular: people were encouraged by the regular clergy to read these books - only the clergy didn't realize that having read the texts people wanted to discuss them independently of the vicar's offical version. Part of the läsare movement was also highly critical of the new version of the Book of Hymns that was published in the early 19th century.
It also has to be remembered that the Swedish Church was a state church with mandatory membership. The vicar was not so much a spiritual guide to his congregation as he was a representative of the state. The congregation may have wanted someone who could preach a good sermon, but the state was more interested in someone who faithfully reported all the statistics the state wanted and who did a good job assisting in tax assessment (if you see the remark utfattig (abject poverty) in the household examination roll, the vicar has decided that this person should be exempt from paying taxes).
As to poverty: by the end of the 18th century the farmers had started to grow two new crops: potatoes and oats. The potatoes were consumed here in Sweden while the oats were largely exported, mainly to England where it was used to feed the many horses used for transportation, above all in London. More food - and more money from the successful export of grain, timber and iron ore - resulted in an explosive population growth, which in its turn fuelled the emigration to America and the industrial revolution here in Sweden.
While there was no super-abundance of food, there was generally enough to feed the fast-growing population (not forgetting the export!). Food production became much more efficient from the latter part of the 18th century, due to land redistribution (skiften) and better tools (like e.g. the scythe). Indeed, in the 19th century Sweden had only three years of seriously failed crops; this was during the last years of the 1860's, resulting in a dramatic increase of emigration and urbanisation. However, it must be pointed out that this was not on a level with the infamous famine years in Ireland: the entire crop did not fail and there were areas in Sweden that were barely affected.
As a matter of fact, Hälsingland was one of the most affluent areas in Sweden: the farmers grew rich growing flax and selling timber (also butter!). The farms of Hälsingland generally have very impressive houses. You can see them at:
http://www.halsingegardar.com/eng/ The same goes for Västmanland and Värmland; there were many poorer provinces, like e.g. Småland, and also the northern parts of Norrland (Norrbotten, Västerbotten).
Ingela