I am sorry that you had to miss the last of your classes. Glad that you are seeing the project through. Hope you are now totally addicted, just like the rest of us.

The distance apart the quilting can be of depends on your batting. If you bought packaged batting, it will tell you how far apart you can quilt it so that it won't shift. This varies by brand and can be as much as 8 inches apart. Other than that consideration, it is totally the decision of the maker.

Do you have a walking foot? That helps a bunch doing straight line quilting. Have fun whatever you decide.