This is an I-94:
http://www.uscis.gov/propub/DocView/afmid/dat/I_94.PDFCanadian citizens visiting the US are not required to fill them in, however it can be to your advantage to have one because it gives you an alien registration number. Various bureaucrats as well as people at banks etc. may ask to see your I-94 and it can help to have one if you intend on staying in the US six months every year.
Like Reba said, sometimes they impose them on you if they think you're going to work illegally, so if you actually ask for one it cuts the conversation short, just make sure the CBP guy actually stamps a six-month expiry date on it.
Costs $6.
On the subject of moving to Nevada, there is a big long thread on here somewhere about buying real estate in the US. You have to be careful because of the taxes.
How it works is that States with no State income tax have high property
taxes (like Nevada and Florida) and States with high income taxes usually have low property taxes (like some jurisdictions in California).
Depending on what your income is going to be it can be to your advantage to live in one place or another. Obviously if you have a high income Nevada makes sense, but if you have a low income California would make more sense, at least from a tax standpoint.
Steve.