But would you say that the first one ("should") sounds too pompous and is best avoided?
I reckon 'shall' is a little old-fashioned nowadays. Sometimes people use it for sugestion or advice but now English persons do not use it. The purpose of your quote it's to know if there is a difference between the both ones.
I think shall is desappearing of the English vocabulary, but I am not a teacher just a French learner.
Would someone kindly explain to me when, in the future tense, is "I shall" most commonly used, as opposed to "I will"?
(Also, do not hesitate to correct any of my eventual grammar or spelling mistakes!)
***NOT A TEACHER***vanity, here in the States, almost everyone uses "will" for future. "Shall" is used usually only in questions (Shall we dance? Shall I open the door?) and perhaps in threats (Oh, yeah? We shall see about that!!!). The famous Henry Fowler said that the only persons who could use "shall" correctly were those born in a certain social class ("to the manner born"). A few (very few) Americans try to maintain the difference between the "shall" showing future ("I shall be in my office at 9 a.m. as usual every day") and the "will" showing determination ("Don't worry. I will be in my office waiting for you at 11 p.m. as I promised"). Although I was certainly NOT to the manner born, I try to maintain this distinction. I do not, however, have the courage to say, "I shan't." Thank you.