For your zone you shouldn't have to dig up the rhizomes this winter. Mine stay year-round and do fine.

They may have burned because they were sheltered at HD and are now exposed to full sun. They'll probably send up some new shoots .............just make sure the water is actually reaching the roots and not running off and give them some MilacleGro.

If they're like most I see at HD I doubt they need dividing.

or you could have leafrollers...do a search on this forum for pictures and discussion.

I thought mine were crunchy, but they were being eaten.

It sounds like 1 of 2 problems:

1) Leaf Rollers - check and see if there are rolled-up leaves that are "stitched" shut, with a material that looks like a spider web. If so you have leaf rollers. HD or Lowe's sell products that will kill them. I use an Ortho spray - a lot of people like powder, because it stays around longer
2) Rust - Does it start out with yellow or brown specks or streaks on the leaves, then gets worse? If so, you probably have rust. It's a fungus, and there is no cure - however, a fungicide should prevent it from advancing. Again, HD or Lowe's sells them - I use a coipper-based one.

Hope this helps.

Steve