Thanks for the tip; by 'get down into the hip' do you mean balance a bit further back by 'sitting' somewhat? Info seem to have my feet run away with me a lot as it were, I end up on my picks quite a lot, so I suspect I'm having the same problem you had.
Yes, I believe that's what she means. When going backwards, knee-bend is very important (it always is, really), because you want to skate further back on your blades, and NOT be up on your toes (there should be no scratching with the picks). The best way to achieve this is by bending those knees like you're going to sit down. You'll be building some thigh muscles, too during this whole process!
You'll get it! Just keep practicing and listening to your coach. Going backwards is a big step.