Major makes virtually no difference in a medical school application. I have two suggestions as to selecting a major:

1. Take classes you find interesting.
2. Major in a field that will provide you with career options if medical school doesn't work out. I initially wanted to major in philosophy and during my first winter break I mentioned this to my dad. He asked me what I'd do with that if medical school didn't work out. I realized he had a good point and wound up majoring in chemistry with a minor in philosophy. If I hadn't gone on to medical school, I would have probably gotten a PhD in chemistry. If I had a philosophy degree, my main option would have been going on to be a professor in philosophy. While that may have been an interesting career, I think I would have struggled to find a job, etc.

As to which school to attend - I'd say go to the school where you will get the best education, and that you can afford. If you do very well at any school, you'll be a good candidate for most medical schools. The only exception would be the very elite medical schools - like Harvard - where your undergrad school probably can be a limiting factor. I'm not familiar with the colleges you mentioned, but make sure you select a school where you think you'll have a good experience and be able to learn the things that you find interesting. If one school is not as good, but is much more affordable, you'll have to make some decisions as to whether the more expensive school is going to be worth the extra expense. Those types of decisions would be good ones to discuss with your college advisor. You can also try to reach the medical school advisor at the two colleges and ask to speak to them. You can see what their thoughts are. While you shouldn't judge the college entirely on how helpful the medical school advisor is, you can at least get some additional advice. I'd actually be interested to hear what they have to say - assuming you can reach them.

The medical school advisors at those schools would also be a good resource for getting an answer to your question about the UW medical schools. From what I've heard, most schools ultimately don't give that much preference to their own undergrad students. They may make that sort of claim, but I haven't seen it to actually play out to be true. The only exception is in situations where someone has done a lot of work/research with a member of the medical school faculty and done an excellent job in their work. A recommendation from a medical school faculty member obviously carries a lot of weight. However, that sort of recommendation would also work well for you when you apply to other medical schools.

As to pre-med requirements, I would save those for when you are actually in college. It sounds like your college credits now are through a community college. The community college science classes are usually not sufficient to meet medical school requirements. You need to take the same science courses that someone majoring in the field would take. For example, it is general chemistry for chemistry majors. And intro to biology for biology majors. You need to take the science courses with a lab as well.

That's just my advice - but remember I am not a medical school advisor, just someone who went to medical school.