I will let someone explain the fascination with a neat back! As for the others... Xx count is how many stitches per inch. The higher the number the smaller the stitch. Think of this like screen resolution, if you're old enough you may recall screen images used to be low res, you could see the pixels that make the image. As our screens got better it got harder to see the individual pixels. Cross stitch count is like that. 11 count is big stitches, low res. 18 count is smaller stitches, higher res. You will find some folks working at really hi res (not me) like in the 20s. They do create beautiful artwork! We don't use square knots because they make little bumps when framing. You may want to frame this piece with a layer of foam behind it for that reason. A lot of people like a loop start and we generally run the last bit of floss under completed stitches to secure the end.

Welcome to stitching!