Couple questions/concerns.. hoping to find out now to avoid a possible ban

[Vyndree]

1. Can we get banned for running together as a group on our 5 accounts since they are different names on the accounts? It will always be him controlling his 2 accounts and me on my 3. Im not 100% sure how Blizzard tells or if they just ban first and not look into it. We are on the same IP address since we live together.

If you're not breaking the rules, you should not get banned.

That being said, GMs are human and they do sometimes make mistakes -- if in doubt, ticket yourself. From what I understand, they keep a record of information and if you readily admit that you and your fiance are playing from the same IP and NOT account sharing then they will have record of that when they do their investigation.

2. Would it cause problems with him using the shaman I created on his 2nd account to begin with? I leveled it with the 2 shamans on my accounts. I used keyclone with them when I leveled, and I remember reading that Blizz looks for the keypresses being sent between accounts in different names. From now on, it would always been him controlling it at the same time as his pally.

If you were account sharing, then you were account sharing. I can't really say whether or not you will get actioned for this or if Blizzard will be forgiving, because that is up to them. At the very worst, they will see it as a form of "powerleveling" and may, at best, remove the "benefit" he gained. At worst? Banned account.

It's up to you whether you want to live with the consequences of your actions or start over from scratch.

3. If him using the shaman I made could get us in trouble, is it possible for him to make another character and level it up, or transfer 1 from his main account? Not sure if my slight blonde moment with using his account has basically tainted it for us to use multiboxing or not.

If he wants to transfer a character from an account that hasn't broken the rules, to another account that hasn't broken the rules, it would be perfectly fine for him to do so. Account actions are precisely that -- per account. If you messed up and got banned on one account, creating a new account essentially gives you a "fresh slate".

Benefiting in any way from account sharing would indeed "taint" the account -- i.e. if you break the rules, you cannot undo the fact that you broke the rules.

4. Would if be better to either just not use his 2nd account at all and just run with a 4 group?

It depends -- "better" is in the eye of the beholder.

Here are the potential consequences for keeping the account:
1) Nothing happens or Blizzard is lenient and gives a temporary ban
2) Blizzard permanently bans the account
3) Blizzard waits until your characters are higher in level/better gear and then bans the account

Do you, in your opinion, find those consequences better than starting a new account from scratch? Which comes with the consequences of:
1) Having to re-level a character

It's personal preference -- either deal with the consequences of your actions or start over.