The plugins may not work with subsequent versions of browsers. In general, this is another thing to avoid. There are a host of html extensions floating around, and plenty of ways to create a page that will only run on one flavor of server or browser. Something like PHP could be consdered, as it's a fairly open standard. Things like ASP should be avoided rather strenuously.
Static pages are fine.
They are the simplest case and again simply won't suffice for most of the interesting apps we hear about. Pulling static pages from a big repository is OK, too. If it makes sense for the app, it doesn't make us uncomfortable. Dynamic page generation implies something much more sophisticated on the back end, pulling information out of some database and creating HTML to serve that information on the fly. We don't object to this fundamentally, but it is worth noting that we don't fully support it now.