The tail that's left over from your cast on can be woven into the blanket or into the edge of the blanket. Don't worry about it for now. You can deal with it when you're finished.
It could be that your sts (actually your knitted piece) is curling because you're knitting a row and purling a row alternately (stockinette st). You may want to add a border of 3-4sts in garter st (knit all the rows) at the edges of the blanket to keep it from curling. 6-8 rows of garter st at the beginning and end will help too. Here's a thread
on knitting that curls and how to stop it that may help.