From Poly to the MK, just get on the monorail. But you'll probably get a three hour parking pass when you park at the Poly, unless you valet park.
You can also park at the Transportation and Ticket Center (TTC) and walk to the Poly. It's about a five minute walk.
From the Poly to Epcot, you can walk to the TTC and take the Epcot monorail. It will be much faster to walk than take the monorail to the TTC.