Sandy, welcome. In that size listening area the M60s should be plenty, although if you're subject to upgraditis the M80s cerainly wouldn't be overkill and would work fine with many receivers, including those Denons. The rest of the speakers are fine as well.
Maybe you could explain a bit more about what specific positioning questions that you have.
HDMI offers single cable convenience, plus copy protection which the industry loves. The all digital nature may or may not result in a better picture than a component connection, since DA and AD conversions are handled pretty well by most players and TVs these days. Note that the 3806 also has the MultEq room equalization feature which may be significantly better.
