I am going to have my air ducts and returns cleaned out. What kind of
results should I expect to happen from this process. The house is 50+ years
old and from what I can see the ducts have never been cleaned. I have one
small dog who sheds moderately. There really isn't a whole lot of dog hair
when I change my filter every month or so.

I have two rooms on my second floor that I have just turned into a bedroom
and a playroom. These 2 rooms never really received good heat or air from my
system, can I expect the air/heat to circulate better to these upper floor
rooms after the cleaning?

Every room has at least 1 return except the bathroom and the front room on
the top floor. The 2 rooms on the top floor each have only one air vent.
Front room is about 14X16
Back room is about 22X16

My house is set up like this

2nd floor - 2 rooms
Main floor - 2 bedrooms, living room, bathroom, kitchen
Basement - 75% finished , laundry room area (where heater is located.)