There are a couple of way to get to the link for finding your other posts. If you click on your name above as the thread starter - a pop up comes up that gives you the opportunity to see your other posts. That being said when I do that this post is the only post I see other than your 2021 posts. The second way is in the upper right corner there is your user name with a down arrow - click on the down arrow - which gives you several links related to your account
Getting to your other question - you will want to leave yourself a little wiggle room but you will not need a lot. I would probably go with 1-2 inches. Assuming you will baste it first, there should not be a lot of movement on the back. The reason that longarmers ask for 6-8 is to load the quilt and have room around the center so that the machine has room to freely move without hitting the clamps that hold the quilt taut.
By the way - welcome back!!