They are only warnings (and not errors). So IMO there's nothing to fix and worry about.
I guess having a consistent layout in all major browsers and CSS validation at the same time is something you can't have at this point... since css3 is not a completely set standard yet and so every browser has it's own way of implementing the features, like for rounded corners theres border-radius, -moz-border-radius, -webkit-border-radius and -khtml-border-radius.
And as far as zoom: 1 is concerned, it's there to fix layouts in the dreaded IE6; by triggering the IE-specific hasLayout flag. You can read up more about it on msdn or here.