A couple of questions

[FredK]

Suppose I don't want to display the last changed date, but the page creation date?

Actually I wanted that too. I believe I do have a plugin somewhere that takes care of that… The reason you don’t find anything about it in de codex is because all there is saved is the last editing time. So if you really want it, you’ll have to code it in, or bribe me to go looking for the plugin I wrote some weeks ago.

*bribe* (if you don't want to look, I'll take a peek at some plugins and see if I can cook up something, but I'm a designer-not-a-programmer, really...)

...

• Use 2 template files, one with and one without the plugin call. Now select a different template on a per page basis.
  

...Take your pick.

Ah, but, see, there is no plugin call to use. If there had been I would'n'a asked in the first place. Promise.

Related to this is the plugin manager - at the moment, as far as I can tell, there's nothing you can do in the plugin manager...

There has been talk about this here on the forum before. People that wanted to be able to just upload plugin straight through the admin panel so it will be simple, in the GetSimple spirit. As internet54 said, the whole plugin part is still in a very early stage so those kind of option have not yet really been looked at.

Understood. See it as a suggestion/feature request then? Something to chew over.