Just Picked Up My 1st TM and Have Toilet Question

Greetings! Yesterday I picked up my 1996 2518 TM and want to thank all you TM vets that have posted so much great info on this site that has helped me decide that TM is the only RV for me and my family.  

I stumbled on to my TM at a local dealership and then found this site to learn all I could before buying.  The dealer had not ever seen a TM either (recent trade-in)so they had to "figure" everything out before my inspection.

From what I have read TMs do not have blackwater tanks but the dealer told me that mine did.  Could this be correct?  It has the Thetford re-cir toilet with the release handle at the base and you can hear the water emptying into a tank below.  Does it all just go to the grey tank?  

Is charging the system as easy as adding water until the dial reads "charge" or is there something else to it?

I can't wait to get to the woods in my new TM.  I understand how everything else works but the toilet is a bit puzzling so I want to have a good understanding of how it works before getting to camp.  Thanks for any tips you may have.