Steven doesn't give you a pickaxe, but he gives you a Beldum...
From steven at his house.
Steven lives in Mossdeep town, by the Pokemon center.
You have to get the Devon Scope from Steven.
In Mossdeep City, Steven will give it to you.
in the cave by the ocean!
Steven gives it to you later on
go to his house in mossdeep
Steven gives it to you at his house.
In Pokemon Emerald, Steven is no longer the Champion. He has been replaced by Wallace, former Sootopolis City Gym Leader. Wallace is replaced by Juan. Steven plays a different part in the story.
No, you only battle Steven because in Pokemon emerald Wallace is the champion.