Here's some answers to your questions.

1. Supposedly UPS is not hiring "flight qualified supervisor" CAPTAINS anymore. They are to start out as F/Os and advance based on their ability. Pay is very good, subject to what you can negotiate like a traditional corporate executive position. No two flight qualified supervisors are paid the same.

2. On call 24x7x365. Work to FAR limits and then some if the company needs you to. Only able to turn down one transfer in your career.

3. A very select few are highly respected by the pilot group. The vast majority are NOT.

4. Job security is variable at best. As long as YOU do what the company wants then it's great. You don't and you're fired. You have no seniority number and cannot go to the line if you get "tired" of working in the office.

Unfortunately, you probably did burn your bridge with UPS. If UPS is anything it's arrogant. They absolutely cannot understand why anyone would not want to work here and you turning them down is a major loss of face for the company.