1st. Ignores mining level if mining like a stone level tool on a stone next to ore of a diamond level.
2nd. I've noticed that the Iron Hammer ignores Redstone that should easily be mined by an Iron Axe.
I am unsure about Diamond Hammers at this point but will update...

1 is a duplicate of #11
I can't reproduce 2, my iron hammer mined redstone ore and redstone blocks perfectly fine