Answers to your three questions:
1. I think exclusion is more appropriate. However, if adding it in doesn't change the utilities much, I think a lot of folks would be comfortable adding it in as part of the estimation as well.
2. It is the utility of the none. I can imagine how you could use it as the anchor to ONE of the attributes, but not all of them. I do not know why you would want to do this, because it would not change your simulations or how you interpreted the utilities - all it would do is recenter the utilities of one of your attributes.
3. How you use it as an anchor depends a little on how the rest of your experiment is structured. For example, if you had a labeled design, then you could just subtract the utility of None from the utility of all the alternatives' labels - the utility for the none option would then be zero and for all your other labels would be those label utilities minus the none utility. If you have brand as an attribute, then you could do this with brand instead - the utility of each brand is that brand's utility minus the none utility and the None utility becomes zero. For example, if you have brands with utilities of 1, 0 and -1 and a none utility of 2, then you would subtract 2 from each of these to get brand utilities of -1, -2 and -3 and a none utility of 0. Note the you have used none to re-center the brand utilities, but not any of the other utilities. I do not know how this will benefit your interpretation of the results.