Regarding the "throwing rocks" part:
For small rocks, i think you can use the shuriken as a reference, dealing the same amount of damage and using the same range increment (1d3 for a medium character, 10ft.). This also goes in line with the rules in CW.
I may be wrong, but i think i read about an exotic weapon called "halfling skiprock", or something like that... Can't remember where, or it's stats, but i'll look for it...
For bigger rocks, you can always look for the entry on "Rock Throwing" in the
giants.
As for the 0 dmg weapons... I don't think you could apply damage to them. Examples: If i throw a thunderstone, the stone is designed to vaporize on impact, so it will. If you throw a (non-frozen) pea or a cheeto (yes, the snack) at someone, it would certainly take a lot of power for it to cause any kind of damage. Either it's mass is simply not enough on impact, or it's energy will disperse as it flies through the air.
Depending on your interpretation of "0 damage", there are the ones that deal non-lethal damage, but you know about those already