CPF354 posted the main facts.
To add, the current Pan Am employees will still all be employed. In simple terms, Pan Am will be what the MBCR is to the MBTA.
Instead of the "Parent" railroad being MBTA, it will be Pan Am Southern. And instead of the company chose to do the actual work (like MBCR is to MBTA), it will be Pan Am. In effect, all Pan Am employees working in the yards, locals and road freights on the Pan Am Southern territory, they will be in effect contractors. Still employed, managed and paid by Pan Am.
As for other details (These are FACTS, not rumours).....
As for a working timeline for the big changes to start, NS's goal is to be able to go from Ayer to Mechanicville in 7 hours in 2 years or less. But it will take alot of time to do site work, order materials, place materials and hire crews. Do not expect double track from Westminster to Deerfield and beyond running 30 or more MPH till at least next summer. This summer the goal is the get the exsisting tracks up to at least 25 everywhere.
As for power, they have 15 SD40-2's coming from Helm soon. Within the next 90 days, probably sooner.