It feels to me like over half of the questions on the site are tagged [dd*]. Yes, it works acceptably, and is probably the best solution for now. It also looks unreadable and silly.
No. It is not permitted because of the way the sites are built. URL special characters like /, & and # are not allowed because tags and handles and titles show up in the URLs to make the site work. For instance, look at the tagging or feature-request links on the right sidebar. The system dynamically builds a URL that includes those tags to let you search.
I like DnD.