How to get MIN and MAX date from table data
Here's a simple method. We use a CTE to get the first and last INSERT_DATEs for each job; then, join to the main table to retrieve the estimated completions dates from those first and last loads:

WITH JobFirstLast (job, first_load, last_load, load_count) AS
     (SELECT job,
             MIN(INSERT_DATE) as first_load,
             MAX(INSERT_DATE) as last_load,
             COUNT(job) as load_count
        FROM ktimov.press_schd
       GROUP BY job
     )
SELECT j.job
      ,f.EST_COMPLETION as first_est_completion
      ,l.EST_COMPLETION as last_est_completion
      ,j.load_count - 1 as times_changed
  FROM JobFirstLast j
         LEFT  JOIN ktimov.press_schd f ON (j.job = f.job AND j.first_load = f.INSERT_DATE)
         LEFT  JOIN ktimov.press_schd l ON (j.job = l.job AND j.last_load = l.INSERT_DATE);


NOTE: I'm assuming that the first load is simply establishing the initial values, and that only subsequent loads are counted as changes. If you really want the total number of loads, change j.load_count - 1 to j.load_count.