Why am I getting slaughtered?

Well, I think the major issue here is your party. It doesn't seem you have changed any of your heroes bar and you have henchmens too. A level 15 hero with a good bar would still be a lot stronger than a level 20 henchmen. I would recommend having 2 healers. Monks or Ritualists, to you preference. If one of them has protective spirit you can manually cast it on yourself whenever you run in and that should help a lot mitigate the damage your receiving. After that, people usually bring a minion master (necro) and a SoS Rit. These 2 will spawn minions/spirits and they will also mitigate a lot of damage for your party. The rest of your team should consist of casters. (usually mesmers since their pretty strong) For the bars I would recommend looking on guild wars pvx. Their not the best but their good for starters. Once you play more, you will really get a good feel in which skills you prefer and etc.

edit: Oh and I forgot. Obviously, if you have some spare money. Runeing up your heroes and equipping them with max damage weapons helps alot. Use survivors insignias if you think they are dieing too much. Giving your heroes runes (ex: rune of domination magic on a mesmer) will also help on the damage.

I might offer an alternative view here.

If your heroes are still below max level and/or you don't yet have the skills unlocked to give them some decent builds you may find that you're actually much better off with a full team of henchmen (and just a minimal number of heroes - a level 20 Mox can be useful).

You may find you have to let your henchmen do most of the work for a little while - but it shouldn't take you too long to get up to level 20 when the balance should start to restore. From there you can start working on builds for your heroes and things should start to get easier. Once you can start to unlock elites things will pick up.

Oh, and it's entirely optional to spend a lot of money fitting out your heroes - you can fit them with a cheap major rune on their major attribute for a very small cost. Anything more than that isn't really needed for normal modes. It's the build that makes the difference and spending a lot of money before you have the builds will be counter-productive.

Edit:
Also, have you made your way to Kaineng Center yet and got yourself a set of maximum armour?

Your armour will be the main issue if it's not max yet. Work on that as your main priority. If its going to take a while to afford make sure you've got the next best from somewhere like Seitung Harbor.

http://wiki.guildwars.com/wiki/Armorer

If you have the cash, I would recommend buying the skill packs from GW store. It'll make all of this a whole lot easier. Reason you are dying is probably because your heroes have partial and/or poor skill bars.

As has been said, if you're heroes skills are weak you'd almost be better off just using henchmen. The main benefit of heroes is that you can flag the top 3 separately (which helps against AoE damage heavy foes) but if they can't do much of anything you'd be better off with the clustering with all henchmen.

Based on the pic, you are looking at 2 separate mobs. You're not charging both of them at once are you? That's pretty much an automatic suicide for a poorly skilled and equipped party.

Also your choice of henchmen may not be the best. Eve doesn't summon minions and most of her damage is focused on single enemies. IMO kinda useless for most areas. In fact I've never used her ever.

If you feel the need to have a 2nd "melee" type to go with Mox, I'd suggest Devona over Talon for this area as Devona actually has multiple knockdown skills which will help against spell casters (who I'm guessing are the one's that are doing you in quickly). Talon's skills are kinda blah for EOTN unless you have a party that utilizes conditions to it's benefit.

Unless you have Vekk all skilled up with potent fire based skills (looks like he's holding either an air or water wand) you'd be better off taking Cynn as she's got a real potent mix of fire spells that so happen to do exceptionally well against water (ice) based enemies (what you're facing mostly here).

Same with Gwen if her skill bar is not built up, you'd be better off with Lo Sha (he'll help when you meet up with Giants with Ineptitude and Shadow of Fear). Also Herta, the earth ele, has a strong AoE attack skill in Sandstorm and the ability to cast anti melee ward that will help against giants as well as a good energy management mix of spells. The hardest part of Norhartt IMO for you isn't really the Avalanche mobs, but probably the wondering Giant mob led by the warrior boss Baglorag Grumblesnort. They are kinda relentless and will chase you down if you get anywhere near them and for poorly built parties they'll wipe you out over and over again.

Use no more than 3 heroes (again assuming they don't have a lot of skills). Only benefit then is really to just allow you to flag them separately so they can possibly take one for the team instead of your more powerful henchmen which will be balled up more likely.

I suggest you keep running heroes over henchmen, henchmen are not that great compared to heroes, even if you have iffy bars for them. And besides, it's nice to have all your heroes level 20 for when you might need them in the future!

I recently did pretty much the same thing, crossed over from Prophecies to Factions with my (then) Lv 16 Ranger, and Warrior; and got stomped. It takes a few trips out to get a good feel for the pace of Factions, but you will.

I find Factions requires a little more control in terms of moving up so Bad guys are at the edge of your Agg bubble, assigning initial targets. Then hitting hard in a coordinated attack. Afflicted explode when they die and its damaging, use range weapons on them as much as possible. If your fighting Jade Brotherhood they are spamming double dragon just now, so I try to pick out and take down their Mages first; once they are down the other Mobs are quite manageable.

Keep at it, the Brotherhood will be paying for your Armor Upgrade in a just a couple days. ; )

A lot of advise is already given. I agree that it's better to use skilled up heroes or henchman in EOTN. EOTN henchman are designed to that place and they have a poretty good skillbar.

The avalanches are hard and they whiped me a few times as well. I think your doing the quest for the ebon vanguard (to get to long eyes ledge). looking at your picture you can hug the right hand wll and slip past those avalanches.

This is why I hate all those "new player guides" that tell people to get to EotN first. It is just too damn hard compared to the rest of the game.