Answer to Question 1
The main group or area would certainly be the Project Management Office or PMO. This group will consist of the project executive, project managers, project schedulers, and administrative staff. The next main area would be the leads of the various project teams. This would include the functional teams, the change management team, the development team, the conversion team, reporting team, testing team, and the infrastructure team. Lastly there are the actual members of each of these different teams.
Answer to Question 2
Two sets of columns are union compatible if they contain the same number of columns, and if the data types of the columns in one set match the data types of the columns in the other set. In other words, the first column in one set has a compatible data type with the data type of the first column in the other set, the second column in one set has a compatible data type with the data type of the second column in the other set, and so on.