What do you mean by a side column?
A typical ballot could have two columns of offices. For each office there are a number of candidates and ovals to mark one's choices. In the column the candiadates names appear on the left side and the voting ovals on the right. It is possible to leave some of the names for races off the ballot if it varies by precinct in the county. Those names can be printed on a generic ballot for the voter during check-in. The printing shouldn't interfere with the scanned ovals.
How would you ensure that I got the right combination of US representatives, state board of education, state senators and representatives, county commissioners, constables, and JPs on my ballot?
In many cases, the district offices are for 4 years, with staggered terms, so I may or may not vote for a state senator, for example, based on my precinct. There are also provisions for removing uncontested races from the ballot.
How would you check for undervotes or overvotes?
How large of ballot paper is required for 100 races?