I empty homes for people in your situation. I use eBay, Craigslist and consignment stores. I hold group garages sales and Estate sells.. It is a lot of work..
To be honest, I have never been able to get rid of all of the collectibles, until I sold them as a bulk item.. I sell as much as possible individually and eventually contact all of the buyers and ask if they would like the rest for a real bargin..
Remember your time is worth money.. You decide.. Is it worth the hours it will take to research, list and keep up with all of the contacts.. And then the packing and shipping.. Again, are you going to do this or hire someone to deal with the hassels? Maybe see if a local Auction house or Estate seller would be interested in buying everything you want to get rid of. Also fif donated.. The value of the donation is all tax deductible..
I would purchase the house. Your daughter will make new friends, she can keep up with these friends through Skype, sleepovers and gatherings..she is only 10, she can handle it as long as you and your husband are happy.. Keep a positive attitude..