Bike Shop or Bike Help

[NE-Stripes]

is it a new chain? if the bike came with it on there it should be the right size. Having been an avid mountain biker for many years a good chain tool is invaluable. If you buy a good bike multi tool they usually come with a chain tool topeak and park make nice multi tools. sounds like an alignment issue to me, derailiers can be a pain esp if the hanger is a little bent.