I can't say how the Runner's Retreat went this year but will drop a note to someone who visited it this year. I didn't care for it the 1st year they offered it and thought this year's sounded better but preferred sitting with the group instead of paying for the retreat.
"1) I am actually not staying at a host resort (WL instead). Will the cabs get me in as close as the buses would have? Are we talking about the Epcot parking lot?"
The buses are still a bit of a walk but it's all good

They don't drop you at the entrance. So I can't imagine a taxi would be any farther. I'd check with the hotel and getting a taxi. Though I know someone on the group had used taxi's for the Minnie in the past but sadly I don't recall WHO did. But it's doable.
"5) What is a timing mat? Will I know it when I see it?"
Big dirty looking dull red mats LOL Ok so my description leaves a lot to be desired but how about a picture? it's the red things in the photo. The 1st one starts the chip and the 2nd registers your chip number and sends off the alert of where you are and when you crossed it.

They haven't added the Runner Alert links yet for the Princess but it's these that will tell your family/friends at home where you are on the course..
http://www.asiorders.com/view_user_photo.asp?EVENTID=40337&ID=60285186
FOOD?!?!?!?! Yes please! Everyone is different and it will take experimenting on your part to see what works for you. I am still getting it down for myself

My typical food for the morning is water, my Special K breakfast bar of all things, I train with it so eat it. A banana!!!! Me lubs bananas. And i bring along a Clif Bar as a back up.
Seems most like a bagel with peanut butter. But for me my stomach on race morning can't handle even the SMELL of the peanut butter. Each race is different. DL I munched my bar and banana before going to the corrals. This Jan I jumped out of bed at 2:30 (or was that 2?) and at my Special K and had no problems. By I think 4 or 4:30 I was getting more nervous and couldn't munch on anything. Now Susan who is a morning person and can eat no problem, had a horrible time this past race. You just don't know. So eat what you know. In the area before you move to the corrals they have porta johns and enough garbage boxes to toss food packaging. They had tables with cups of water too.
The lady with the special PASTA request... no answer but I'd suggest calling the hotel and asking to speak with someone at the counter service about special meals. It's at Port Orleans Riverside right? Boatrights the sit down is there too, not sure if the counter service doesn't work if the Boatrights can handle special requests easier and you can get it to go when you explain you are meeting with a group in the counter area. Give a call. Worst they can say is no. The best is you will know in advance and one less worry. Good luck!!!!
16 min mile pace.... hopefully they will use the flag system again. I have heard pretty good things about it.

But here is hoping NO ONE SEES THE FLAGS!!! POSITIVE THOUGHTS ONLY!!!!!!! Keep putting those feet one in front of the other. Stay positive! And remember the most important thing... YOUR RUNNING AT DISNEY WORLD HOW COOL IS THAT?!?!?!?!?
Happy training!!! Stay healthy!!!!