Is there way to sort questions on "unanswered/my tags" page by date? There is a "newest" tab, but it's shows all questions, not only with my tags.
If you want every tag that has Perl in it:
You can manually craft the URL and then bookmark it.
`https://stackoverflow.com/unanswered/tagged?tagnames=tag1 tag2 tag3&tab=newest
Someone 'just' posted a question about standardizing all the page's tabs to feature tabs like newest on every page. Considering it covers a the same (and a little more) ground than this request, you might want to go upvote it.
Okay I've started playing with this through trial and error and I've made some progress:
This still has the AND problem but its a start.