I'm not following, is the HTML group a design group or a development group? If it's design, then #1 and #2 are good.
There may be some other things to ask for depened upon who the consumer of the HTML will be. Think of javascript rules
(yes, no - to what model), graphics rules (little, lot, provide psd files not just flattened gifs or jpegs), and CSS rules (valid, hacks well documented, selectors well named).
I think the use of validators is great but agree on the one(s) you'll use up front (the last project I worked on, the agreed upon validator was "looks good in IE" - ug).
