I came across a problem with growing a metropolis last night. 1: Is it legal to grow the metropolis in such a way that it will contain a hut or village? And 2: can you then use the square for trade or production before it is cleared?
The rulebook does not state anything about this, only enemy figures. We interpreted that you are allowed to grow the metropolis but not use the square with the hut.
Actually, I do believe the rulebook (at least for the core game) clarifies this. A city (when it is founded) may not contain enemy figures/tokens of any kind, and unexplored huts and villages fall into this category.
In short: NO, your cities/metropoli may not contain ANY "foreign" figures/tokens.
P.S.: I can also explain in Danish, if you need to.