The important thing about hand quilting is to keep your stitches even. It isn't important how tiny they are, unless they become toe-catchers!
I use my index fingernail to quilt toward me, and my thumbnail to quilt to the right and away from me. My thimble gets used when stitching to the left. Yep, I wear holes in my nails a lot. I've also worn holes in two thimbles, boy what a surprise that is when the needle suddenly stabs you!
Regarding preprinted panels, test a few small areas with a damp towel to see if the marks disappear when you first receive it. If they do, you can remark the lines with a disappearing marker after the areas air-dry. Do NOT use a hair dryer!
I SO admire those tiny hand quilted stitches made by some. And I've seen some handwork that looks just like machine stitching...but where is the point in that?? I'm happy with my 10-to-the-inch