Yes aliases, please. Useful for multi-language tagging as well.

Yes. The most options to automate tagging, the better. But I don't agree with Aye Nonomous. Complex filtering is not interesting in this case if we are looking to speed up the tagging process.

In addition, some improvements should be considered. For example:

also apply them if they are present in other fields: Like from & to. For example, when you send an email to support@domainexample.com, then (if support and/or domainexample.com matches) apply the tags.

Apply the tags to the selected email (at the same time when the tags are assigned). Currently, it's necessary to apply them again later.