there's no fixed number but if you spend over 6months in thailand without a proper visa, you might get pulled apart at the airport to figure out while you come here this often. You should consider to apply for a multi entry tourist visa which can guarantee you up to 9 months in the country...
not hard, as european you can live in whatever european country you like, as for your wife, I believe she needs to get a visa/certificate by sweden and with that she can freely travel all over europe