when are you officially 'man and wife' (aka married) ?

I'm pretty sure after you take your vows then consummate the marriage at least the Bible says you have to consummate the marriage before you are officially man and wife.

All what you have stated is part of a marriage ceremony .In certain countries in addition to the marriage ceremony the marriage is registered with the Registrar of Marriage in order to give legal effect .

You are married once you go through the steps to have an officiant preform a marriage ceremony. You can get married without hosting a huge party. That would a reception with invited guests.

Oh, by the way ... the saying " man and wife " is out of style because to have someone pronounce a man a man on the day he gets married is ridiculous. He has beena man all along, right? Sure, pronounce her the wife because that is appropriate, considering the purpose of the ceremony. Therefore the only and correct way to say it is "husband and wife ". Ahem.

In the US. Technically it is when your signed wedding license has been filed with the state.  They then send you a copy of your wedding certificate 

It's when you're pronounced married by the officiate. Of course it can't be when a proposal happens as some couples break up before the wedding or just continue on as "fiance/fiancee" for decades.  

The proposal is legally irrelevant. The ring is legally irrelevant. You are married when you have fulfilled the legal requirements for marriage.  In English-speaking countries, that basically means: 

1. Being two people legally able to marry, you have applied for and received a marriage license. 

2. You have exchanged consents (ie, I, X take you, Y to be my spouse) in the presence of someone legally authorised to perform marriages and the required witness(es). 

In practical terms, there's also some paperwork to be signed and submitted.  Whether you have a traditional/religious ceremony or a non-religious one is, legally speaking, irrelevant.  People who are married in church by a priest are exactly as married as people married by a civil celebrant, marriage commissioner, or JP. 

You're legally married when you sign a wedding license, and or when you submit the license for a marriage certificate. 

When he proposes, you're not married but you are engaged until you decide to get married. 

It's when all the legal paperwork has been signed, it becomes official after your officiant turns it in to the courthouse/city hall (whomever issued it).

We went with "husband and wife" because well, he was already a man.

It's when you sign the certificate to legally join you together (legally, anyway)

when you sign the marriage papers.....