I'm sure Dave will provide you with a great answer.  In the meantime, I've got a few tutorials on modes.  The first addresses the concept at a high level & deals with some of your questions.  Short answer, you've got the right idea & you can use modes in a variety of ways depending on your musical goals.

https://www.guitartricks.com/tutorial/370

The others are more practical application of each mode in turn.

https://www.guitartricks.com/tutorial/770

https://www.guitartricks.com/tutorial/2630

Hope that helps!