Now that's a great post! This is what film-making is all about.

Check this: http://www.scriptmag.com/features/columns/legally-speaking-it-depends-ri...

Your reel doesn't have a point: are you good at directing action? Sci-fi with vfx? Actors giving stellar performances? It is a bit of everything.
I would cut much less and allow for the segments to "breath", maybe join the 3-4 shots of each movie together and make them evolve into something worthy. Since the cinematography is not equally good in all clips, at least do not cross-cut all the time.

In such ignorant comments you can go with humor
e.g. "it's not the size that matters, it's the technique!"
or you can go with sarcasm
e.g. "I have never worked with such unprofessional actors. All the others had more experience, were more talented and acted much better. It's impossible to get good performances from you guys".

There is no definite answer here - some people find them important and helpful and some don't use them at all. For the ones who use them, they can be as simple as stick figures or as complicated as 3d animatronics / previz. It's a matter of personal preference and way of working.

Where is freedom of speech? Some may find his posts interesting, some may not. Since you can see who posts what, before clicking on it, there is no reason to ban him - just ignore him if you feel so. He never said he is not self-promoting and AFAIK there is no such policy and guidelines against self-promotion here.

As for the same questions asked over and over again, there should be some kind of guidance for the beginners. Either a "sticky"/pinned post, or some content-related suggestions before posting. It will be better for everyone since maybe there is a more detailed thread already posted - for example I am not going to devote my time to answer again, if I have already given a detailed explanation for the same subject in another post. People need to be reminded about the "search" function, it seems! ;)