[MunchkinMan]

In the future, it will make things easier to break up your questions into smaller chunks. We prefer one question per thread, or a small group (2 or 3) of related questions.

Rather than correct any mistakes in the above response, I'll just answer all of your questions with the official answers.

1. Events occur in order, almost always. You can't normally react to card being played unless the card you are using to react says you can (for example, Wishing Ring can be played to prevent a Curse from taking effect). This means that you can't decide to become a Cleric after someone plays Divine Intervention. There is an exception to that very specific case, and it happens only at the beginning of the game, when everyone is building their characters. We discuss that in the FAQ.
2. A Mate is always continuously copying the Monster it was played on. If you play Illusion on a Monster and change it, you will change its Mate to a copy of the new Monster. If you play a Monster Enhancer on the original Monster after Mate was played, the Mate gets the Monster Enhancer added to its combat strength as well.
3. What Pukachu is saying that if you have enough combat strength from your Level alone to kill it, then you get the extra level. Any bonuses, no matter the source, that are required to get you to the combat strength you need will cost you the extra level. So, you must be Level 7 or higher, to defeat an unmodified Pukachu. Obviously, a Warrior could be Level 6.
4. Helping a player has a very specific meaning in the game. It means joining the combat and adding your combat strength to the fight. If someone wants to play cards from outside the combat that would help you (like a potion or a Monster Enhancer with a negative value, like Baby), that is allowed. What Gazebo won't allow is someone to actually join you in the combat.
5. You can choose to ignore the Stoned Golem at any time during the combat. Nothing on the card indicates that the ability to ignore him is a one-time offer.
6. The Hireling from Munchkin (Deluxe) and Munchkin 3 is a special case, since it has text on it that gives specific instructions. This means, for that card, you don't have to worry about the rules for other types of Hirelings that may contradict that card. But, it also means that if you lose Hireling, the Item goes, regardless of how that happened.