If you're not sewing them together, but making a scarf or something, you doing a border would be good, but you don't have to for the squares. For a scarf you'd knit about 4-6 rows then about 3-4 sts on each edge. For your squares 3 rows ought to work.
Blocking is getting your item damp or wet, then pinning it into shape and let it dry. It doesn't work with acrylic, only natural fibers.