If someone asks what is essentially a follow-up question to one (or more) already on the site, I'm not sure that it makes sense to direct a user off-site to get the background the OP wants to provide. Good answers to that question should have not only links to external sites where appropriate, but also background and explanation to support their use, so it seems to me that we would want people to link to other good answers and questions. (This is especially true if the new question is the result of someone commenting "You should probably ask this in a separate question!")

I would think that references to game experts are certainly appropriate, although perhaps more valuable if there is an appropriate citation ... if someone asks a question about how to play K-10 offsuit in Texas Hold 'Em, an answer that says "Chris Ferguson prefers to ..." is more valuable if it includes a link to a page or a video or something that actually shows his opinion, as well as some explanation of it.