1.) Is it true that if you find Calculus, Linear Algebra, and Differential Equations easy then the rest of the university curriculum in Mathematics will too? I mean they're all pre-requisites for each other, so that question logically follows.

2.) How much studying comes after graduating with a Ph.D in the major?

3.) How easily does solutions to unsolved problems come after graduation, specifically for someone who can easily get a 4.0 GPA in everything?

4.) Are all university undergraduate and Ph.D programs generally the same in rigor and content?

5.) What will it be like to be a Ph.D graduate at age 37, as in will I find work easily, will I have social challenges, will I feel remorse?

Thanks!