It appears that all three of these features could be accomodated with a little hacking on the template tags. The property tag doesn't currently evaluate the chunk between the tags, so that's why you couldn't include a multiple tag in between the open and close tags.
Have you tried passing a property up to an including template. Just based on a cursory glance, it appears that it might already work. I haven't tried to follow all of the ins and outs, but it appears that properties are stored in the same tcl array each time a template is evaluated. I haven't worked out the order of evaluation, due to recursions of template evals, to see if it works out correctly.
