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!