Yes PvP is for a part stat based, but stats are making you only twice(maybe 2.5 with end game gear?) as strong at lvl 60 compared to using nothing. And it's very easy(few hours) to get good enough items. The main advantage of having stats from gear in PvP is that you can use different builds, making PvP a lot more fun.
As far as I know there is a ?feat? that allows mark to stay after you block a hit. So I assume block goes away as soon as you get hit (even on block). It has nothing to do with the skills you use on the enemy. Keep in mind, mark only increases your aggro gained by other skills, so if you do no damage, you still don't get…
Do you have negative defense? As far as I know it is: <name> deals <damage taken> (<damage before damage reduction>) That are all the guardians skills with highest damage, compared to other classes it's quite low for the highest damage. I normally miss 50+% of my melee range skills, so the dps is a lot lower than those few…