Opinions? Those I have...
1) When designing or installing a Home Theater system, are DVI and/or HDMI cable runs always included in your plans?
I am always looking at trying to fture proof my cabling installations. I run Cat6 ethernet, RG59 cable and HDMI.
2) For DVI and/or HDMI cable runs, what is the:
a) Typical cable length you use--- I try and stay at less than 3 m. Longer runs are more difficult to manage and signal degradation becomes an issue.
b) Maximum cable length you have used successfully--- 10 m works for me.
c) Maximum cable length you really need--- With planning most runs need be only 2-3 metres.
3) Do you need to pull DVI / HDMI cable through conduit? If Yes, is this a frequent requirement?
My preference is to use conduit for a couple of reasons. Easier to use later, easier to insulate around, vermin resistant and it lends itself to mapping exact locations of all components.
4) In your opinion, what percentage of the total system price should be set aside for all audio and video cabling?
You should plan on at least 10% with 15% being the norm and 20% the max. There is a diminishing return at the higher levels that only true geeks will even try and notice.