All the people who got fired and offered to be rehired should agree to refuse unless their salary is doubled - if only because decent employers don't play with people's livelihoods like that, to teach them a lesson.
They should, but government positions are to a PayScale. You get hired "as" a GS-9 or whatever. You can go and lookup what the location pay adjustment is for your city if you're curious.
Contractors are generally paid at least double digit percentages more for the same job but can be fired/not renewed much easier. In theory.
The tradeoff was that it's pretty hard to fire a full time employee without cause, and the pension / student loan forgiveness / etc.
There are also a bunch of contracting arrangements where the workers are W-2 employees of a private company that has a contract with the gov to provide bulk professional services from said employees.
Those workers have some room to negotiate salaries and benefits like any private sector worker. Although the terms of the big contract can put some limits on what the private company can offer.
A lot of national labs and NASA stuff works like this.
While that sounds nice, that's not going to happen. It simply isn't in the budget. They might be able to get a 10-15% raise, or a one time bonus to make up for lost wages. But I wouldn't expect more than that.