When storing values, will I always have to use int myVariable?

Answer 1

No. You replace int with the datatype you wish to use such as char, bool, float, double, void etc. Using int will store a number or "integer" value, meaning it has to be explicitly that and not the alternatives.

Answer 2

The "naming convention" is primarily best if its meaningful. For example, If you're creating a variable that will store a rounded version of "pi" then it makes sense to name your variable:

float pi = 3.14;

Instead of

float number = 3.14;

This is basic programming practice.