1. Can you use one of the attacks as a secondary attack if using a weapon?
2. If you can with #1, can you do so if the weapon is a 2 handed one?
3. if so, could this all be done as part of a full round attack?
Beast Totem, Lesser (Su): "While raging, the barbarian gains two claw attacks. These attacks are considered primary attacks and are made at the barbarian's full base attack bonus. The claws deal 1d6 points of slashing damage (1d4 if Small) plus the barbarian's Strength modifier."
Natural Attacks: "You can make attacks with natural weapons in combination with attacks made with a melee weapon and unarmed strikes, so long as a different limb is used for each attack. For example, you cannot make a claw attack and also use that hand to make attacks with a longsword. When you make additional attacks in this way, all of your natural attacks are treated as secondary natural attacks, using your base attack bonus minus 5 and adding only 1/2 of your Strength modifier on damage rolls."
1) Yes.
2) No. Both hands will be occupied with the weapon. Barring some weird case with extra arms, of course.
3) It would have to be. A standard ("Attack") action only gets you one attack, which you could choose to make with your manufactured weapon or a natural weapon (the claw would be primary in this case). A full-round ("Full-Attack") action gives you all your attacks, which is where you are going to get combinations of manufactured weapon and natural (in this case, secondary) weapon attacks.
