If 15 people answer this question, you'll get 15 different responses. The buses are scheduled based on need and arrival times. You may go directly to your resort if the bus can be filled with guests for that resort or if no one else needs a ride at that time.
I have used DME twice, once to ASMo and once to WL. On the ASMo trip, we boarded the DME bus and pulled out less than five minutes later. The bus was not very full. We stopped at Sports, Music and then Movies. All told, it took about 65 minutes from the time we stepped off of the plane until we stepped off the bus.
On our WL trip, we sat in the bus for about 25 minutes until it left. People kept straggling on. In fact, the driver closed the door to leave, and a group came running out of the terminal. He had to load their bags, etc. The bus was almost full by the time we left. That trip took us about 90 minutes from the time we deplaned. WL was the first stop. When we departed, we also stopped at Poly and GF.
I think it is safe to assume that it will take about 90 minutes to get to the resort from the time you get off the plane. It could be longer, it may be shorter. As for the number of stops, that's all depends on load levels and destination.
Enjoy your trip!