You don't choose targets for Loamcrafter Faun's ability at the time it triggers
The only other time you go into your Extra Deck, at least for a pure Ancient Warriors Deck, is if you are going first and are making Number 41: Bagooska the Terribly Tired Tapir or you are going second and you are making a Rank 4 to punch your opponent before putting a Divine Arsenal AA-ZEUS - Sky Thunder on top of it because you dont have enough damage to OTK this turn
Conversely, if you copy a spell without casting it, you won't include that copy's mana value in the amount of damage Call Forth the Tempest deals
As for me, I get to travel around quite a bit in March
If Summon: Fenrir has two lore counters and you remove one, you don't retrigger Chapter I
It contains everything you need to start playing straight away, including a detailed instruction guide to help you master the rules of the game