I'll try to help where I can!
My first runDisney race (and first distance/timed race ever) was Tink this year and I was put in the second to last corral so there's hope

With your pace I'm sure even if you are in the last you should be fine.
I can't help with question 2 as I didn't wait in any character lines, sorry!
Not directly in the finishers area. I think they were referring to wandering the parks and finding characters there (Disneyland has the wonderful advantage that their characters walk around the park willy nilly, in addition to those noted in the specific character locations on the maps, for example I saw Captain Hook wandering around the esplanade around 4 p.m. and Alice and the Mad Hatter & Peter and Wendy often frequent Fantasyland)
RunDisney will stop allowing others to pick up packets after this year's Avenger's so you should be fine as long as you/she fills out the Packet Pick Up Authorization form found on rundisney.com
Info on the change:
http://www.rundisney.com/blog/articles/packet-pick-up-update-03-24-14/
They supply you with a mini Ziploc baggy with four safety pins when you get your bib which you secure to the front of your shirt. (after filling out your emergency contact info on the back of your bib)
There is sometimes a pile-up at the beginning of the water station tables but if you continue to run just past those there will be volunteers ready holding cups in both hands for you to easily receive without hassle.