Okay, Haven't read it all, but after a few weeks, newspaper is fine (been there, used that) once they get good footing. Just use common sense, if some are slipping, keep them on some grippy stuff for another week before trying it again.
Towels, cloths, or rags are all fine and dandy for like TWO DAYS. You'll get REALLY sick of washing or replacing them hourly.
Shavings fail the edible test, yet for some reason, ducklings didn't get the memo, and WILL try to eat them, sometimes becoming impacted and dying. (NOT TO MENTION THE MESS THEY KICK UP!!)
Straw is good, but make sure it isn't really fine, or they may try to eat an entire stalk and get it stuck in their crop.
And with shelf liners, you have to disinfect it regularly, because the poop doesn't fall through, and it gets stuck; which means a good place for Cocci and other baddies to hide in. Not to mention it stays almost constantly wet, which cracks their teeny tiny baby feet, and makes them sore.
I've found keeping them on wire (if you have something to catch the junk) is the best, as long as you make sure it isn't drafty AT ALL until they're mostly feathered. Even then, I don't think a drafty area is very well suited to raising ducklings or any other bird for that matter.