hi pyropingvin,
your second wish (unlinking text frames) has already been implemented by cezary... but is not yet in 1.5svn
bugs.scribus.net/view.php?id=10295
for the second one, i think that we should extend the "insert > frame dialog" instead... it does not need much... on can already load a file and spread it over multiple pages!
but it could also be done with a script...