Hi there! I'm a a PhD student in education psychology at UIC. My program involves less counselling, and more quant data analysis. We tend to look at scoring models, evaluations and ed data. To answer your questions:
1) Job prospects are pretty decent - check the Association for Institutional Research site, here: https://www.airweb.org/Careers/Pages/Jobs.aspx
2) Sure, I believe you can land research analyst jobs or similar position with an M.Ed.
3) Education Testing Service, Pearson's, survey companies
4) No idea..
5) I guess it depends on if you plan to be a teach at an R01 institution. If you're planning to work in the private sector, it doesn't appear to be a big deal.
6) Debt? Maybe pick up an RA'ship?