What are these "portholes & panels" on the fuselage of the Omega Tanker DC-10?
The things circled in red are static ports. They are used to measure static air pressure. You can see a close up (from a different aircraft) here:

(taken from this answer)
What you circled in green is an outflow valve used for controlling the pressurization. See also:

What is this device below the door of a 737 (and other aircraft)?
How does the outflow valve work on a cabin pressurization system?
How does a DC-10 flight engineer manually raise the cabin altitude?

It is technically called a Thrust Recovery Outflow Valve:

The actual nomenclature is the &quot;Thrust Recovery Outflow Valve&quot;
[...]
The thrust recovery outflow valve is essentially the valve that controls cabin altitude throughout the isobaric selection range. It can be controlled electrically through 2 electric motors receiving input from the automatic and semi-automatic cabin pressure controller/computer. On the -10's with Flight Engineers, the clutches could be disengaged via a handle at the FE station, and the valve was then controlled through a manual wheel.

(Airliners.net)
Both items are unrelated to the fact that this is a tanker. The following image shows the same items on a Northwest Airlines DC-10-40:

(Airliners.net)