Seniority is not based upon facility time. Your seniority is the first day in which you report to your first facility after leaving the academy. There are some exceptions, like if you report to your facility prior to going to the academy (which doesn't happen too often anymore), and once you're at your first facility any "bad time" (staff or supe time) doesn't count and is deducted if you return to the bargaining unit. But when you transfer from one facility to another, your seniorty date remains unchanged, you simply merge into the seniorty list at your new facility wherever your date falls in their current list of bargaining unit members.
As for transferring, at a Center its very difficult to get out. In the terminals much easier. And in recent months there have even been bids open with big incentive money plus a paid move offered for those at slower facilities wanting career progression. With a promotion, your facility manager cannot hold you back, even if the facility is short-staffed. They can keep you for awhile, but cannot stop your progression. I have seen managers give really unrealistic release dates and discourage the gaining facility from picking folks up, but once selected, they can oly hold you for (I think its) 90 days or so (I could be off on the exact amount of time, but its something close to that).
When bidding on controller jobs, you get points for:
(1) the level of the highest facility you've worked at (multiplied by 3: for example if your highest level facility was an ATC-10, then you get 30 points)
(2) you get one point for each of the following up to 5 points, if you have them: private pilot cert, comml pilot cert, instrument rathing, CFI, dispatchers license
(3) 2 points for each full year as an ATCS-2152,
less one point for each years since CPC level was lost (if that applies, and/or less one point for each full year since you worked in a terminal or center facility (if that applies)
(4) Education in 3 parts
(a) Formal education - the highest point value of the following, not commulative:
1 yr college - 3 Points
1.5 years of college - 4 Points
2 years college - 5 Points
Associates Degree - 6 Points
2.5 years college - 7 Points
3 years college - 8 Points
4.0 yaers college - 9 Points
Bachelors Degree - 10 Points
1 year grad work - 12 Points
2 years grad work - 14 Points
Masters Degree - 15 Points
3 years grad work - 17 Points
Doctorate - 20 Points
(b) FAA Correspondance Courses (You must be an FAA Emplyee to take these, cannot do it prior to being employed by the FAA): you get 1/4 point per each course up to a maximum of 2 points
(c) Long-term training: You won't get this EVER in your career. I do not know anyone who ever has during my 22 years in the agency. It does not include the time you spent at the academy for those of you trying to figure out how to manipulate it.
and finally (5) Up to 10 points for a variety of awards that you may earn during your career in the FAA (old exceptional and superior ratings, time off awards, incentive awards, quality step increases, etc).