In response to the max stealth for a barb. It's not a mandatory issue with them. It is a handy tool though. More to the point if you plan on getting into instances and eventually raids, you want to max out subtlety to lower the chance of having your damage pull aggro of of your tanks. As the above poster said, there is an ambush from stealth but it isnt as powerful as it used to be. I would keep a pretty serious amount of stealth up for a barb, but not necessary at end game PvE to have it maxed. The barb is a pretty versatile class. High stealth sometimes allows them to sneak right on by serious problem areas when shadows are present or it is night time. It wont give you much extra damage per se, but it can't hurt to have high numbers. Bottom line, no it's not necessary to keep it maxed, but it does come in handy when the stealth score is fairly high. Hope this helps some. Let me know if you have any other questions. ~ Khadoc (the husband of Morrigan).
I think a carnage conq/zerker barb would be pretty effective. Although if you stick with the necro/barb combo you'll see how powerful necro's are at solo/leveling. (I've leveled all three solo) The coolest part of conq/barb would be that you're both smashing faces next to eachother.
Any ideas on what would work best with a sin? Another sin? She was wanting to try a Set priest and I am wanting to try a sin with it to see if it worked. I was thinking the same principles of classes that use auras or some kind of melee debuff or melee buff would work well with one.