An American marrying a Canadian

Here is my situation, I'm an American and my fiancé is a Canadian citizen. She came to the states on vacation, we fell in love and we are in the place we are today, but her 6 month travelers 'visa'/Canadian exemption is about to expire before we get married. My questions are these

1. If she stays in the US beyond her allotted time and then we get married after the expiration, will this affect her greencard processing or eligibility to stay in the US?

2. Will it affect travel across the borders while the greencard is being processed?

3. If it will affect her status, are there any forms I can file to keep her here legally during processing?

4. Will she have to return back to Canada during any of the processing to ensure an approval/future legal stay?

I truly appreciate any and all advice.

1. If she stays in the US beyond her allotted time and then we get married after the expiration, will this affect her greencard processing or eligibility to stay in the US?

What was her intent when she entered the US for her last visit? Did she quit her job and sell all her stuff in Canada so that she could stay and marry you? If so, this could negatively affect the outcome of a green card application. If at a green card interview it is determined that she entered the US with intent to get married and stay, her green card can be denied and she can be deported with no avenue of appeal.

2. Will it affect travel across the borders while the greencard is being processed?

If she has overstayed, she would be recommended to NOT leave the US for any reason before she has her green card.

3. If it will affect her status, are there any forms I can file to keep her here legally during processing?

You will have to file adjustment of status forms regardless of her status when you get married.

4. Will she have to return back to Canada during any of the processing to ensure an approval/future legal stay?

Again, this will depend on her intent when she last entered the US and what kind of evidence you both have that she DID NOT intend to stay and get married without the proper visa.

check out http://www.visajourney.com for info on marriage based immigration to the US.

Your best bet may be to have her return to Canada before her time is up and then petition for a fiance visa.

You should consult an attorney as your situation is complex.I would recommend not leaving the US at this point unless she wants to stay abroad while you file the green card petition and thus for a year.By being there so long she clearly doesn't hold solid ties to the US.Therefore you need to file an extension of the visitors status asap even though her original en=try might not be documented and then you file a petition to sponsor her and adjust her status from non-immigrant to immigrant.You should also file concurrently an employment document as well as a travel document which usually take 90 days to get.
Good Luck and do consult

There is no extension of stay for Canadian visitors.

If they were to get married ASAP and send in the applications for adjustment of status, this in effect extends her visitor status until her interview date.

It would still not be recommended to leave the country if they choose this route, even with AP.