1. I am management so can't comment on this with respect to computer science but I would imagine that you would be able to apply for MIS jobs. I think it would be much tougher if you wanted to try to fill a strategy, IB, or management position.
2. I have heard that it is generally more difficult for PhDs from outside of the US to get placements at US institutions. However, the schools you are considering have strong name recognition so this may be less of an issue. Additionally, a good CV is a good CV so as long as you've got a good publication record then this will be less of a concern for you.
3. This is really up to you. It could be a good strategy to apply broadly and then make this decision once the dust has settled in the Spring. Oftentimes it is made for you based upon where you are accepted/rejected. If I were in your shoes, I would probably target a US PhD in a business school but I am pretty risk averse.