Well, since the view will look just like a table when done, you will only get one resultset with one set of columns. Therefore, if you want to add together several result sets into one, that's fine, but they must all have the same number of columns and datatypes. Furthermore, the names for the columns will come from the first selects.
Therefore, if you must 'fill in' the missing columns for each select, and name them all in the first select.
--TO_CHAR(NULL) AS COL3,
--COL3 AS COL4