#1 If you are going to stipple or do any of the other meandering stitches, normally, you don't mark. But if there is a stencil with a design, you mark it. And hopefully the world will NOT stop rotating, but I do leave my feed dogs engaged. NEVER had a problem.
#2 Yes, that sounds like it is the correct foot.
#3 There was a post over a month ago about someone using the 17067CLR-VP hooks to hang a small quilt. You might want to do an advance search and enter COMMAND. You could then find out who started the post and send them an email with your questions.
#4 My advice!! Two things you need to accomplish for good FMQ. First, get in tune with your machine so that when you try free motion, you can imitate the speed in which your sewing machine would move the fabric. Don't EVER be in a rush. Secondly, don't look at where you needle is but look an inch down to where you want to go. You can not guide you quilt unless you are looking ahead. Think of it as driving a car. You look down the road to see what is ahead., where to make a turn. Hope this makes sense. It is what I was taught and it has helped me be successful with making some very nice quilts. Good Luck and be sure to enjoy yourself !!
