The document quoted above was the same one I got, so if its circulation was restricted, then it wasn't marked as such and wasn't particularly controlled.
It doesn't say anything on the page above that line about the 75% / 25% share. I read it as Teesside foots the bill for the operation and Eastern takes 25% of the ticket sales to pay for its aircraft costs, but I may be wrong.
There's still no sign of any flights on sale, which is very odd. There is also no mention of Flybe in the document which is very odd. Are Flybe fully on board with this or are Eastern going to somehow need to resurrect their own booking system for this? The flights aren't going to get very far if no-one can book on them and there was nothing to say that tickets would be on sale from a set date on a set website. It's all a bit odd.