Dwarven slayers want an HONORABLE death in combat. That means that they will wear enough armor so that not any goblin will shank them in the back, but not enough that they can survive great big clubs. Pathfinder light armor is perfectly fine for slayers.
DR is better than the higher AC. Because when they hit, it won't matter the number, they just do. So anything to lessen the damage, like DR, or stoneskin, or rage HP, or miss chances from cloak of displacement, will all layer up to help you out.
Raging brutality feat, if you get to 13th level, will be amazing for you for damage. Your con modifier added to your damage rolls, and 1.5x if 2-handed weapon is used.
Cloak of displacement, ring of for focus- for better AC and saves, will help you tremendously.
Bracers of sworn vengeance are nice to have to do some more damage, extra 2d6 per hit is nice.
Rhino hide, if you choose to charge.
Higher AC from ioun stone that add +1 to AC, higher des, better armor, ring of protection, necklace of natural armor.
Power attack is always nice. Raging vitality is also a good feat, although not sure for first level.
Go Invulnerable Rager Archetype.
A no-armor barbarian is really going to be quite squishy during the low levels, especially if you play it in keeping with a 'slayer-esque' approach of charge and to hell with the consequences.
Your only real hope is to drop the opposition before you get dropped yourself.
Make sure the rest of your party is ok with you being a suicidal glass cannon though... you will tend to be a huge healing sink at low level as most everything will hit you whenever it attacks.
It gets easier if you manage to start climbing levels, and Invulnerable Rager is really where you want to be. Since you'll be hit so much the DR shavings off each hit will really stack up and you'll get good value out of it.
I'd avoid Improved Initiative, as Barbarians are relatively feat starved at low levels. Raging Vitality or Toughness are probably your best options for Level 1 for survivability. Power Attack would be more useful to increase your damage side of the equation.
Toughness, Cleave, Power Attack. Rage powers depend on how your character will fight I personally like Superstition, Witch Hunter, and Ghost Rager.
Depends what point buy / rolling method you're using.
If it's point buy then I wouldn't go over a 12, unless you're getting 25 or 30 points, then it might be worth pushing it to 14.
If you're rolling I'd go Con>Str>Dex>Wis>Int>Cha for ability priorities.
Take Con and Str. Toughness feat and the +1 hit point let you HP bloat and DR overcome what AC you would have. Also try armored kilt and hide or leather would provide some AC but still fit thematically.
Diehard would make you die quicker as you would keep fighting rather than drop unconscious to be healed up later.
Guarded Life is decent enough, but I'd think the first couple of powers should be offensive in nature.
After all you want to build a Barbarian that actually fights... rather than just safely gets whittled down into negatives then automatically stabilizes no?