I lived in Columbia for a couple years and open carried for a couple summers; including on Broadway downtown....
1} No permit needed to OC at the state level, and I never had any problems in Columbia.
2} Cities are allowed to ban OC so you have to know the city you are going to and check them out, Columbia is OC legal
3} a GREAT source for Missouri handgun information is http://www.missouricarry.com and a great bunch of guys to get to know
A} As you are in Columbia, DO NOT patronize "Target Masters" the owners and management (along with Todd Burke of Tactical Training Specialties), were behind a last minute, behind the scenes secret screwing up of the CCW qualification requirements last year (I use to work there and know the players).
B} If you do not have your Missouri CCW and plan to get it Tim Oliver at http://www.learntocarry.com would be my hands down choice (say hello to Tim and Scott from Bob).
C} If looking for a bank, Boone County State Bank is CCW/OC friendly.