Accepting Islam is not a matter of minimum or maximum conditions.
If one accepts Islam willingly one wouldn't only say the shahada, but pray and fast etc..
As abu Hanifa -as was mentioned by sheikh 'Omar 'Abdulkafy in a lesson I've attended- said to his neighbour who was Zoroastrian who loved to drink (alcohol) but intended to become a Muslim and this was his only opposition to Islam: "Become a Muslim first and we'll see".
The other day the man came and said: "I'm a Muslim, so how about alcohol?"
Abu Hanifa said: "Now you are a Muslim if you got drunk, we may apply hadd (punishment) on you!"
So being a Muslim means taking Islam as a whole not partly. Note that I doubt the attribution of the above story to abu Hanifa, but this doesn't change the lesson one could elarn from it.
Allah actuallyinformed us those who pretend being a Muslim:
O Messenger, let them not grieve you who hasten into disbelief of those who say, "We believe" with their mouths, but their hearts believe not, and from among the Jews. [They are] avid listeners to falsehood, listening to another people who have not come to you. They distort words beyond their [proper] usages, saying "If you are given this, take it; but if you are not given it, then beware." But he for whom Allah intends fitnah - never will you possess [power to do] for him a thing against Allah . Those are the ones for whom Allah does not intend to purify their hearts. For them in this world is disgrace, and for them in the Hereafter is a great punishment. (5:41)
And he also informed us about the hypocrites:
And when they meet those who believe, they say, "We believe"; but when they are alone with their evil ones, they say, "Indeed, we are with you; we were only mockers." (2:14)
A Muslim is only allowed to marry a chaste woman: Either Muslim or from among people of the book. Note that the later kind is somehow vanishing as many Christians and Jews these days can hardly be considered as such.
Assuming this woman accepted Islam she would need a Muslim guardian -as her family are neither Muslims nor from among the people of the book- for your marriage you may need an Imam who may play the role of this guardian and two witnesses and the agreement of both of you to marry each other.
Beside marriage is an important step in life one should think twice about the person one wants to marry and about the possible future with this person. One should try to seek advice and du istikharah too.
The Prophet (ﷺ) said, "A woman is married for four things: for her wealth, for her lineage, for her beauty or for her piety. Select the pious, may you be blessed!". (Riyad as-Asaliheen)