On the subject of base assignments...do the US flight attendants have bump-and-flush in their contract? AA does not. No one can transfer to a base unless there are actual openings in that base. That's why I was surprised to get DFW out of training in 2000. There are transfer lists for each base in seniority order. The transfer list to a base must be cleared of everyone on it before new hires can be placed in that base. The class which graduated two weeks ahead of me in mid-August, 2000 was the first class since 1992 to place a new hire at DFW.
For AA flight attendants who don't know what bump-and-flush is...
Say, AA decided to close the STL f/a base. Bump-and-flush transfers say that any f/a in a closing base can transfer to any base which has f/as junior to them. If this results in overstaffing at the new base, the most junior flight attendants are "flushed" to a base they can hold or furloughed if they are the most junior f/as in the system. Of course, the furloughs would occur only after the contractual furlough prevention steps--leaves of absence, partnership flying, etc--had been done.
For US flight attendants who might want to transfer to DFW after the JCBA takes effect, assuming that our current system stays intact, we have a system of domestic mutual transfers. Say you are based at CLT today, but commute from DFW or another city in Texas. Well, there are a number of AA flight attendants who commute from CLT or RDU who might want to be based at CLT. You put your name on the transfer list for DFW. They put their names on the transfer list for CLT. Every other month or so, Crew Planning works the transfer lists for mutual transfers. Each list is worked in seniority order and f/as are matched up for transfer. Barring unforeseen barriers (you do not get the transfer if you are not in flying status on the first day of the month in which the transfer would be effective) you get your transfer. Being on vacation on that day is not a barrier (if I remember correctly). Being on a leave of absence or on the sick list is. If you are not in flying status, your name remains on the transfer list, but they offer the transfer to the next most senior person on the list who did not get paired up on the first pass.
And, of course there are straight transfers available from time to time when a base staff drops below whatever number Crew Planning determines is the minimum optimal number of f/as for that base. For instance, when an early out package is offered and is awarded in seniority order, DFW and LAX tend to be affected more than other bases because they (for the most part) have the most senior f/as. Straight transfers are also offered in seniority order, and buyer beware...Don't get po'd at your supervisor and put your name on the transfer list to another base and then forget you did it. If your name comes up, a transfer can not be refused; so, you would be transferring to that base for a minimum of 6 months.

(It happened to someone I know.)