You mean in conversation? Honestly, not very often. In speech we normally use "will" for the future tense (I will, he will, they will...), and even shorten it to " 'll " (I'll, she'll, that dog'll...). "Shall" sounds slightly archaic and 'proper'. Warning: do not follow my advice in your own speech until you've listened to some movies or TV shows to get an idea of exactly what " will / 'll " sounds like. For writing, using "shall" as explained in your textbooks is perfectly fine. You can always afford to be precise in writing. :)

Yes of course, you can use both "shall" and "will" to express future action. although however, when you use "shall" to express commitment, it is more effective and convincing. just think of what General McArthur stated: "I shall return!" Is it more convincing than "I will return!"? :)

I've heard people often use 'shall' in medieval movies. Sounds elegant(in a sense) to me although I'd not use it in daily conversation.

yes sometimes i use "shall" for example:-I can ask someone -Shall we talk? Shall we go? like that :) correct me if i am wrong...

Yes. "I shall.." and "We shall..." are used to express the future. We can also use "I will..." and "We will...". they are correct and mean the same too.