1pm on a weekday, are there human (not machine) ticket agents ? If getting off a train coming from NJ, where is the indoor ticket office - same side as that track or the other track/side?

At 1 PM ticket agents (people) are working. Traveling southbound you will have to go up and over the train tracks to get to the station. Stairway or elevators to the skyway. Also if going on to Wash DC buy a ticket on MARC train not Amtrak. MARC is less expensive.

Yes. Ticket machine is inside brand new station

As said earlier... if going to Washington or Baltimore from BWI train station, you can use the MARC commuter train rather than an Amtrak... MARC trains are commuter trains and far cheaper than Amtrak trains... Approximately $7 to DC or $5 to Baltimore... Amtrak prices vary, but the cheapest Amtrak price would be triple that of the MARC fare.