The bus service at the GF is about the same as other deluxe resorts. You take the monorail, or boat, to MK. You can take the monorail to the TTC and get the Epcot monorail. So, you end up only taking the bus to AK, the Studios, DTD and the water parks. The buses come every 15-20 mins or so. They aren't bad at all.
As for DME...it's a bus, with other people on it. It may stop at CR, Polynesian as well as the GF. I have heard some say that it goes to the GF first but that isn't etched in stone.
The average times from deplaning to resort checkin is about 70 mins...that can vary depending on which stop your resort is. All in all it's a very good deal. I personally love it...I had a towncar booked for my dd's first trip to WDW next week (she's 31, can you believe she's never been before??), but I canceled it and decided that DME would be a fun way to start her vacation. She should have the fun aspect vs the luxurious experience.