Per Diem during initial training? Looks like the answer is no. However, other language in the contract seems to indicate you may receive eight hours per day on days you are in training. I'm a pilot, nor a lawyer, thus I'm having some difficulty interpreting the language of the contract.
As for new hires after the dust settles? My guess would be yes.
Finally, it's hard to tell what will be the junior base. Since the L10 will pay more than the other aircraft if this passes (currently, it pays the same as the 757), some people may decide to go for the cash. Since JFK is an L10 only base, it may not be the most junior one.