Tips?

I'm new to Terraria and am unsure as to what certain things are.
I have a ton of questions and if you guys could answer any of them it would be greatly appreciated.

Is the Extractinator any good?
Can you break the ground in Crimson or Corrupted biomes?
Where do you find keys for the biome chests?
How do you go into Hardmode?
Does Hardmode make the monsters more difficult?
Has anyone here gotten the Slime Staff, because of how rare it is? (I do not have it but have seen it on the wiki)

Other general tips would be appreciated as well.
Thanks.

Extractinator can be found in random chests underground. It's used for turn Slush and Silt for gems, ores, etc.

If you are new, I suggest using Sticky Bomb. When you will get crimtane/demonite you can make pickaxe which can break ground.

You need Key Mold which is dropped by mobs after defeat Wall of Flesh and Plantera.

You need defeat WoF.

Yes, Hardmode adds more aggresive mobs. Also your hallow and crimson/corruption will expand faster.

Thanks

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