How does the bite attack from the 'fangs' talent work, with other abilities, actions and features?

Question

The species hybrid—lupine has the special talent fangs that says:

Once per round, the agent may declare he is making a bite attack against his opponent as a free action. This attack inflicts 1d4 standard damage and has a threat range of 20. When the agent uses makes [sic] a bite attack, all the agent’s attacks this round suffer a −2 penalty to the attack roll. (Dark Inheritance pg. 98)

I can fill in some of the blanks here, like reading once per round as once per round on her initiative count and that an agent can only employ the bite attack against a target within the agent's reach. However, I am hung up on two things:

1. For ability scores, class features and feats, is this bite attack an unarmed attack, a melee attack, or a new third path? For example, does the agent add her Strength modifier to the bite attack's attack roll and, if successful, the bite attack's damage roll?
2. Is it legit for the agent to make all of her other attacks normally then take a free action to make her bite attack? (To be clear, unless the agent also has something like the feat Combat Instincts, this order of operations would typically make it so that she suffers that -2 penalty on attack rolls only with that bite attack.)

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Note: Dark Inheritance (2004) is a licensed third-party campaign setting for classic Spycraft (2002).

Answer 1

For the specific questions made on this:

1. Attacks made with natural weapons (bites, claws, tails,...) are considered improved unarmed attacks, as they don't generate an oportunity attack, they do lethal damage and they are made without the use of a proper weapon. On many games and books these are emphasized just making that almost every creature that uses natural weapons has the improved unarmed strike feat. However, on a point in time I don't exactly remember, this became a fact in the rules. So yes, the strength modifiers for attack and damage are added to these attacks (although I've seen some games and books where certain bite attacks added only half strength modifier to damage).

2. No, that's not legit because, although actions can be executed in any order, they has to be declared before starting to execute any of them, so if you declare that your character is going to make a full round attack action and a bite attack free action, it doesn't matter the order in which you execute both actions, the fact that the bite attack free action is being executed affects the attacks for the full round action, even if the bite executes afterwards. You can attack your enemy with -2, kill him before even biting it, at had to bear with the penalty because you had the intention to bite him and you prepared your body, your stance and your attack pattern to it.