I can only think of six, the other possibly being Dark Ritual - and if you think Ritual is a problem remember what's coming at the end of this list
Quite the contrary, you can build a weird deck using a strong commander as your starting point
The reduction of the foretell cost applies only to generic mana in the foretell cost
In EDH, there are popular go wide token commanders in various colors, including Jetmir, Nexus of Revels, Kambal, Profiteering Mayor, Adrix and Nev, Twincasters, Caesar, Legion's Emperor, Marneus Calgar, Cadira, Caller of the Small, Zinnia, Valley's Voice, Arabella, Abandoned Doll, and Aang and Katara
Killing your commander will slow you down, but with good timing, theres only so much removal for your opponents to use
will require you to track energy and radiation, which can be an extra layer of complexity for newbies