The World of Warcraft Armory

I normally do ~4.5k or a little less in 10 mans, around 5k in 25 mans if I don't lag like crazy (which I usually do, my computer sucks). Is that about right for my gear level? I just got my T9 shoulders last night, so I haven't DPS'd with them yet, I previously had Valorous Dreadnaught Shoulderplates - Item - World of Warcraft.

Obviously I'm stacking Armor Penetration, and I've been seeing a noticeable increase in my DPS as I get more, but my Crit Percent has been dropping, mostly through changing to Sword Spec and upgrading a couple pieces that had Crit on them. Now I'm at 28.63%. Is this too low for Arms DPS? I know that Crit isn't the most important stat, but 28% seems very low, even considering that it will be higher with raid buffs. Is there a point where if Crit is low enough it becomes more important to get it higher?

I've been noticing that with the combination of Sword Spec and my low Crit, my rage generation is very unpredictable; one second I'll be completely rage starved, and the next I'll be scrambling to use up 100 rage before wasting more. Would getting my Crit higher help alleviate this problem?

Are there any particular pieces of gear with some nice Crit/Agility on them that I should be shooting for?

Sorry for the wall of text. Any replies are appreciated.