No; it does not take precedence. You will never see alt attribute values on hover in any browser that follows the HTML specifications for these attributes because that is not what alt attribute values are there for.
No; it does not matter if alt attribute values appear on hover. It’s of no real consequence to users of browsers that may do that and it does not change our approach to their use or non-use according to the status of an image.
Although, you should keep in mind the limited value of title attributes. Never use them for anything remotely important.