Good slingshot ammo but not as good as Sapphires, I've seen one of the previous partners at Billabong Blue use them as slingshot ammo, had a bowl full of poor quality ones just for that purpose.
Yeah - flat on the bottom and sort of domed on the top is fairly common among agate nodules. Saw em open, you might find something very interesting inside.
Yes, they are agathes.
Not sure the big one will be interesting, it looks like it is mostly white crystal, but the smaller one shoud have at least interesting color if not a nice pattern.
These beauties remind me of chalcedony that has been molded in clay flows.Is there any evidence of clay where you found them? I have rocks that are almost identical.. they are grey chalcedony with clay remnants and often have ironstone inclusions.