Frizzy ends are the worst! When I was braiding, sometimes the hair would tangle up and I had to throw it away and start a new braid. I secured the braid with a rubber band (you can kind of see them above each curl where the braiding stops) so maybe try rubber bands?
The curls might also be due to the type of hair I used? I bought this hair off of Amazon (the only major downside to it is that the shipping was unreliable, the hair came three weeks later than expected) Here is a link to the braiding hair
I hope this helps! Best of luck!