First thing; you can take the same class from 5 different teachers and will always learn different things. You have to do what you feel comfortable with and realize there is no such thing as the quilt Police even though some think there are. There are some who feel that the way they do things is the only way to do it but in quilting as with most things in life; there are many different ways. If you google each of these things you mentioned you'll get lots of debates and opinions as to how to do them. You'll find what works for you and go that way. I always pay attention to what is being taught in class but decide for myself if it works for me. Like, I pre-wash only fabrics that I think may cause me trouble in the end. Some never pre-wash and others always do. I think walking feet make your life easier and I love using spray basting. Thats my way of doing it but you'll have to find your way. Any machine can do quilting, it's straight lines for the most part and even though some are hard to quilt on, there are quilters who make it work because thats what they have or thats' what they enjoy. Keep taking the classes and learn about the different options you have but then do it the way it's good for you. I love taking classes and I always learn something new and incorporate only what I feel good into what I do. Good luck and since you were doing well before, keep on going in that direction and you'll be fine