I'm surprised someone hasn't responded! Folks usually respond quickly here.
With the baby blanket, they're probably having you use circular needles & just knitting back and forth rather than in the round. You can get alot more stitches on a circular needle & you may need the extra length, depending on the size of the blanket.
My *guess* on the other thing...it may be that they're having you join after
the first row may have something to do with how they want you to sew it together later??? Maybe reading through to the end of the instructions may give you a clue.