[Bug] Can't build parties

Playing an Empire game, I noticed I was unable to build parties.  I had a level 3 city and picked up the first party technology.  The box never un-greyed for a party of more than 1 unit.

Also (possibly my ignorance), the "Imperial" tech tree was unbelievably short.  I finished the tree off except the advanced "Majesty" line, but still had no better buildings than huts.  I found that between the lack of housing and the higher pop-cap (500 for Empire where it was 400 for Kingdom) it was unfeasable to get even one city to level 4.  Is this intentional?  I didn't see anything about it in the manual.