Arkham Horror: The Card Game

No, but if you are engaged with one or more ready enemies, any action other than Fight, Evade, Parley, or Resign causes each engaged enemy to make an attack of opportunity. The attack happens after you pay the action’s costs but before its effects resolve (pp. 11, 38).

A normal successful Fight action deals only 1 damage; weapons and other effects may increase this amount. If the test fails, no damage is dealt—unless you attacked an enemy engaged with another investigator, in which case the failed attack’s damage is dealt to that investigator instead (p. 14).

No resource cost is paid when committing a card, and only icons matching the tested skill—or wild icons—provide bonuses. Each other investigator at your location may commit no more than one card to the test (pp. 15, 33).

Usually, yes: an enemy is spawned ready and engaged with the investigator who drew it. Exceptions include enemies with spawn instructions and aloof enemies, which spawn unengaged (pp. 19, 33).

Yes. During the first round, skip the Mythos phase and begin with the Investigation phase; subsequent rounds follow the normal four-phase order (p. 11).