So, first and foremost, the both of you need to start crafting. Bracers, Gloves, Amulets, and Shoulders. Archon plans of strength (barb) and int (WD) are super cheap. I imagine you both have some Demonic Essences saved up, so you should be able to craft some upgrades quickly.
Secondly, for individual gear… (realize that these are just my opinions; others may have different views).
For you, I would suggest buying a Skorn with Int and Life Steal. I haven't checked prices on the low end, but I imagine you can get a low-ish DPS one for cheap. If you can find one around 1200 DPS, and you put a decent sized emerald in it, you will notice a few changes with your build. First off, your survivability is going to jump quite a bit. Even though you will lose health because of your vit rolls on your knife and mojo, you will notice an increase in how long you can stand there grinding your foes. Also, you will notice that your mana issues become moot. With a low attack speed, you won't need Blood Ritual and you can put on Spirit Vessel. SV will allow you an extra life, as well as allow you to cast Spirit Walk more often. Next, you can change your Soul Harvest rune to Vengeful Spirit, which acts like a free health potion and hits pretty hard, too. You can also drop Horrify-Frightening Aspect and put on BBV-Slam Dance. All of that should make the grind go faster.
Try to drop the random resist on your Zuni chest and pick up an armor or Vit roll. Your EHP stats on your pants are going to hard to make up elsewhere, but you don't need the LoH with a Skorn, so you can try to pick up something with armor, all res, vit and int, as well as two sockets. Cheap rare pants can be had on the AH, but to make up the EHP will be tough for cheap. Depth diggers might be an option, but they can be pricey with the right stats. I would check it out though. Eventually you will also want to buy a Witching Hour with decent EHP stats, too, but prices get steep. The random resist on your boots could be vit, amor or all res…but I'm not sure the price range of those. Realize that the more Vit you have, the more your Life % bonus is going to help. It might be more beneficial to get Vit at this point.
The good news is a lot of the gear you need is going for cheaper than usual because of the expansion. In time, you can get there.
P.S.- Keep in mind you can keep using a 1H + Mojo, no shame in that, but you can pick up a good Thing of the Deep for really cheap, relatively speaking. I know that they have average damage of 200+ for under a mil, which could be a big upgrade. Look into that if you chose that route. I used to run 1H+Mojo, but Skorn changed my perspective and my ability to run higher MPs with ease.
As for crafting, look for Vit, armor, and all res on your shoulders. Similar stats on you bracers, but with crit chance. Crit chance and crit hit on your amulet and gloves.
In the end, you want about 700 All Res, 3500 Armor, 60k HP, and 200k DPS (can probably get by with 180k with a 2h weapon).
Now, for you Barb friend…
I'm not going to be a ton of help here, but his biggest flaw, in my opinion, is his build. Whirlwind is so easy to play and powerful, that it almost seems silly not to play. Check out my barb and ask him to try it out. Have him play it like this: Ancient Spear to generate fury, cast Battle Rage, then just just start whirlwinding and casting Run like the Wind and Overpower (in that order).
As long as he can survive, he can run Rend instead of Ancient Spear…takes some getting used to, but it can be really OP. At lower MPs I would actually suggest it, but I like Ancient Spear because it lets me get into the thick of it more quickly.
Again, I am going to suggest a Life Steal Skorn for him. This will allow him to drop the IK belt and pick up a Witching Hour. The 4th piece of IK gear isn't helping him, so he might as well drop some EHP and get some DPS. He should also pick up either a pain of Inna's Temperance (pants) or Lacuni Prowlers (bracers) to add movement speed…this will help with his whirlwhinding.
Also, I would try to get a ring with Crit Chance and Crit Damage, Strength and Vit (or Armor and All Res)…
I think, if memory serves me correct, he should shoot for 600 All Res, 60k HP, 6000 Armor, and 200k DPS. Those, I think, are stats for MP10. My barb can only run MP8 efficiently, but survives on MP10 for the most part.
Anyways…hope that helps some. If you have questions, get ahold of me in-game. I can help you out on the AH, if you want.
For the both of you, do you know about d3up.com? You can look at raw numbers for gear you are considering buying before you actually buy it. It's really nice. Diabro3.com will tell you which MP they suggest you run, which really means face roll, but I generally run an MP or two higher.