Shall indicates a bit of uncertainty: e.g. 'Shall I go to the park today?' - unsure if you should go to the park or not Whereas will is very certain (and mostly indicating a future tense). e.g. 'I will go to the park today' - you are definitely going to go to the park.

will = future tense shall = used in "cute" and "gallant" requests on very rare occasions in American English 99.5% of the time, you will use "will". Forget the 0.5% (shall) for now.

Well it depends on what pronoun you are using. Usually in traditional grammar we use will when we use second and third person pronoun i.e. he, she, they, yadda yadda yadda. Shall is used for first person pronouns like I and we. The verb will is used in a number of ways, but we chiefly use it, followed by the infinitive of another verb, to talk about the future. Still, you don't really need to worry about this much especially in speech because people tend to contract words. "I shall go home" becomes "I'll go home" and "you will take me there" becomes "you'll take me there". It's barely noticeable unless you're talking to a die-hard linguist so don't sweat it. Good day!