The SIM Card can only be used for data, not for calls. The 30 day period starts with first usage, so you can order it in advance.
With this SIM card you can NOT use the "personal Hotspot" functionality many phones offer.
Of the 4 network operators Telia, Tele2 , Telenor and 3 (Tre), Telia has the best network coverage. In bigger cities and most of southern Sweden all operators are nearly equal as good regarding coverage, but in Northern Sweden Telia is recommended.
Standard European frequency bands are used and all operators offer LTE on their networks.