Bedding should be non slip, something with traction to prevent splay.
I start with potty pads at least the first week to keep a close eye on their poop. Towels are good but alot of changing & washing, some use the non skid mats that are used for lining shelves. Shavings is fine but they do kick alot up into the water, alot of changing, I've read many like the bedding pellets. You need to use what's best of you .... I've done papertowels but potty pads are the best cause is absorbs alot & they do get water all over.
Chick grit is good since they'll peck & attempt to eat everything.