Places to visit are Kalam, Ushu glacier, Mahodand lake. From Mingora a road takes you to Malam Jabba which is a popular ski resort. 16 km from Mardan is a place called Takht Bahi which is popular for its Buddhist ruins. Plan your trip so you can visit Malam Jabba and Takht Bahi on your return journey.
Trout is available all along the Swat river. But you can make a short stopover at Bahrain. There are a lot of good restaurants over there.
There are a lot of good places to stay in Kalam. I have the number of one hotel located in Kalam. Don't remember the name of the hotel but you can call and inquire about accommodation and other things. Call: 0936830089.
Here's a map for your reference