http://www.visajourney.com/content/guideshttp://www.visajourney.com/content/compare comapres the
k1 and cr-1 visas
One can visit the USA up to 6 months--its is not a RIGHT though, up to the port of entry (POE) officer. Bring strong ties that you will be returning to canada (return air fare, apartment/house lease,, letter from employer etc etc) They may not ask for it, but be prepared. Your going to VISIT!!!! not live-----huge difference in the POE officers eyes!
And yes one can goto the USA and then STAY and do what is called adjust of status (AOS) BUT one has to have had NO INTENTION of staying! All I will say about that! Some drawbacks are that u cant work right away, nor can u leave the USA without the greencard approved or u get advance parole (AP) but I believe it only takes a few months to get.
We have had members on VJ that came on a k1--where they cant work until they get EAD (Employment authorization document) BUT they were told they could still work remotely for theeir Cdn company! No clue if thats totally true, they said they contacted soem govt office and said it was fine! Not my problem, as I came on a CR-1.
Read VJ, lots of free info on relationship visas--esp look over that compare link. cheers