I'm a dental hygienist, so I'll do my best to help you out!
1. Depending on where you are in the country dental hygiene can vary from being ridiculously competitive to ehh, you do the pre-req work well and you get in no problem, it's all geographical. If there are more schools to less students, obviously your odds are higher. I went to a 4-yr institution and got my BS in dental hygiene out of high school, so I am unsure how the community colleges work, but if you apply to the programs that offer a BS, no doubt they will be harder to get into, everyone wants a piece of that pie. Can't say much about your chances, since there aren't any numbers, EC's, etc. to go by. So I would set up meetings with the schools you are interested in and have them take a look at those, so they can better tell you where you stand. If this isn't feasible, call them and you should just be sure you've hit most of the points they expect of applicants, to have a good chance of getting in. Not completing all your points shouldn't be a huge problem, if you have, generally done well.
2. This is all up to you! You want to be a hygienist, go big now, while you can, apply to schools in and out of state, that you know you would like to attend. If you have the resources to do so, the more schools you apply to can't hurt. If you don't get in, why not try again?
3. Go for the BS, at the end of the day it is just better to have all around. Not sure where you are located, as mentioned previously this plays a huge role but the state in which I practice, you have an associates, you're in like the 95% that cannot do much of anything else other than hygiene and that's fine, I guess. I knew in the future I wanted to go to dental school, to make life a little easier, I needed a bachelors, I also knew I might want to dabble in higher ed. and public health. In the future you may want to get involved with lets say public health dental hygiene, things of that nature, you need, minimally, a BS.
As stated above, Kahr you're right. Washington is one of the states where there is a broader scope of practice. California is also notorious for this as well, and they don't like to let outsiders in
it's totally doable but it's a long, complicated, and difficult process, especially if you aren't from the West. Take home message on this one, if you apply out of state try to stay on the side you're from, east, west, south, wherever. Hygiene licensing can get unnecessarily sticky, so this makes licensing a lot easier later on.
Best of luck! You will love it!