I've seen some of the posts you mentioned in the past and you seem a credible source so thanks for the update.
Surprised about the Capacity though. Contradicts quite a few things i've personally heard and would also be a massive let down if the club were settling for a Stadium on a par with Newcastle and Sunderland as opposed to the rest of the big clubs, bar Man United, with West Ham also having close to 60K now.
Can't see how they could possibly justify anything less than 55K and that was the proposed number for the Kings Dock when we now have record season tickets sales so that is the only thing that surprises me about your post and makes me think that maybe your contact is not giving everything away there. Would expect closer to 60K than 50K personally.
I think that contact - who don't forget isn't at the Everton end of things - has told me everything he knows. Everton may well be working on something bigger than 50k. But in terms of what he has been privy to, it's been 50k max