I'll put down a few pointers to help you along:

• Nearly all Swedes are perfectly happy to speak English. Not all are as good at it as they think they are, but most speak it fairly well.
• Most Swedes will gladly answer questions you have about customs or "dos and don'ts", so don't be afraid to ask!
• When visiting a Swedish home, remember to remove your outdoor shoes when you get inside. If you want to wear shoes indoors, bring an extra pair. Also, a small gift (a bottle of wine, a box of chocolates, a small potted plant or the like) is appreciated but not necessary, and is not needed for an informal get-together.
• It has been pointed out to be by non-Swedes that many Swedes are huggers! The first time you meet someone they're unlikely to hug you, but from the second time on it's not unlikely.
• Most Swedes are uncomfortable talking about how much money they make, their religion, or their political beliefs. There are many exceptions to this, but avoid bringing up these subjects yourself.
• Dating is very informal in Sweden.
• Swedish society is quite collectivits on the national level with many tax-financed services, but highly individualistic on the level of the individual. Family ties are a lot less important than in many other countries.
• If you want to get to know Swedes outside your workplace or study program, you'll probably have better luck by joining a club or taking an evening course than by going out to a bar or café.

I hope this helps!