Pine shavings are fine for bedding. They keep the poops from smelling too much between cleanings, & they help keep warmth in the winter. THey can get a little expensive if you have a lot of chickens or a big coop, however.
DE is Diatomaceous Earth. It's made from crushed up tiny little microscopic sea creatures' shells, as far as I know. It can help if mixed with the litter to control fly & beetle & tick populations in the coop & mites & ticks & lice on the chickens. It breaks down the chitin in insects' body armor --I think-- & causes them to dehydrate. It's fine for chickens & humans to eat a bit of with food, IF it's FOOD GRADE. You can find Food Grade DE online. Do a keyword search. I think there are links on this site also.
When dusting your chickens or coop with DE, please wear a dust mask, as it is a very fine powder which can irritate the lungs.
Also, please be careful not to spill it on any ground you care about outside, because it will kill a lot of the beneficial bugs & microorganisms as well.
I dust my chickens on our gravel driveway, just so most of the DE goes into 6 " of gravel & not on the roly-polys & ants.
You can mix a inch of DE into the chickens' feed as well, if you use mash or crumbles at all. It can help kill or prevent internal parasites. I do mine once a week. I don't know what's best, bbut some other people here do, I think.
Good luck