Mulligan this deck aggressively.
The deck is similar to a combo deck with 2 Combo pieces (Loam, Acceleration). So you should mulligan nearly every 7 card hand without both pieces or one piece and Intuition. A hand without acceleration, but with good lands, Loam and Intuition is not optimal, but on the play I would keep it.
If you have information about your opponent, that changes things of course (for example having Zuran Orb vs. Burn or Tabernacle vs. Elves is almost always a keep).
Playing around Extirpate is nearly impossible. If your opponent plays other spells with Mana Cost 1 and you KNOW he has Extirpate you can try to go for Chalice at 1, but usually it is nearly impossible to play around. Extirpate is just a very good card against this deck. If you have Crucible in your sideboard, side it in of course.
Both are pretty much for what the cards say ;)
Crucible is sided in against decks that get rid of your loam, against the mirror and against control decks. Smokestack is good against slow decks with few permanents like Bant.
If you suspect that your opponent has no Wastelands (like Zoo), you should recur it with Loam every turn so that you can go for the win aggressively and take no creature damage (or Chain Lightning damage). Against aggressive decks with Wastelands (Merfolk, Goblins) or ways to counter your recursion (Bant) use it to buy you a couple of turns, but don't ignore board control or they will keep a Wasteland in their hand and kill you in one attack. Against these decks you have to figure out every turn what is the best play based on the board, there is no easy way. Sometimes you just have to gamble that they dont have Wasteland, sometimes you can play around Wasteland.

