I had a HP photosmart back in the day that I liked, until a new version of windows came out. They would not update the drivers. So my fairly expensive printer was now a brick. I will never buy HP products again.
No. I will never go back to a cropped sensor. My shooting style doesn't require the 5d3 AF, bit low light performance is a must. If I were getting paid to shoot wildlife, I would consider it. I think the 7D2 will be great. I had the original and liked everything except the ISO noise.
I've had good experiences with eBay. I've only sold 3 items (7D, 70-200 f4, and 24-105). It is a lot harder to get scammed nowadays. eBay holds the paypal balance for a short period after the sale to protect the seller and buyer to help prevent scams. Your seller status determines how long this period is. I usually get my funds a day or two after the item has been delivered. The key is having good photos and being completely honest about any wear or scratches. I purchased all of my gear on eBay and have had zero issues, but I usually buy from top sellers.
I would gladly invite the 5DIII to swing over and party with me and my 6D. We would have lots of fun interchanging lenses. I would treat her like a goddess. Perhaps 6D would get jealous, but I'd love them both.