Buddha's Teachings on Life's Purpose and Existence

I have been ruminating about some existential questions...."what is purpose of life"...."is there a creator"..."what is the best work for a mortal to undertake in their lifetime"...."is suffering from unnecessary burden of study or job justified if they are not bringing satisfaction but are necessary for social survival"... etc, etc. In what sutta(s) has Blessed One talked about this matters? what solution Master gave to get out of this vicious cycle (referring to the vicious cycle of "ruminating about some existential questions.")which drains the energy?