Does the reach increase of the Eldritch Claw tattoo stack with Fangs of the Fire Snake?

The Eldritch Claw tattoo released in Tasha’s Cauldron of Everything includes the Eldritch Maul ability which grants the following benefit:

For the duration, each of your melee attacks with a weapon or an unarmed strike can reach a target up to 15 feet away from you, as inky tendrils launch toward the target.

The Fangs of the Fire Snake elemental discipline also grants the following benefit:

Your reach with your unarmed strikes increases by 10 feet for that action, as well as the rest of the turn.

After activating Eldritch Maul and using Fangs of the Fire Snake what is the reach of my unarmed strikes? Would it be 25 feet or would it be 15 ft?

What creature has the sharpest fangs?

I was working on an analogy in a sales pitch to a blacksmith.

"I can make your longsword sharper than the fang of a …."

My immediate reaction was to fill in the blank with a dragon. I ended up choosing the Fang/Gray Dragon.

Is there any creature in the MM that is considered to have the sharpest teeth in the DnD Universe?

How do the fangs of the lupine work?

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 98)

I can fill in some of the blanks here, like reading once per round as once per round on her initiative count and like 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.)

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

How does the Way of the Four Elements monk’s Fangs of the Fire Snake elemental discipline work?

I’m confused by the wording of the Way of the Four Elements monk’s Fangs of the Fire Snake elemental discipline.

Specifically, how long does its bonus to the reach of unarmed strikes last, and how many times is the extra fire damage applied?

Here is an example scenario, with how I think it works:

  • A level 8 monk gets 2 attacks on his turn during the attack action, and a bonus action for Flurry of Blows, giving 2 additional unarmed strikes and a total of 4 unarmed strikes on his turn for 1 ki.

  • If he spends 1 ki for Fangs of the Fire Snake, the unarmed damage changes from bludgeoning to fire damage, and the reach is increased to a total of 15 ft.

  • When the monk’s turn ends, Fangs of the Fire Snake ends, so it is not possible to make an opportunity attack with this discipline.

  • If I hit with an attack I can expend another ki to add 1d10 of fire damage. This extra damage only applies to that singular hit, the next attacks don’t have the extra fire damage, and I can’t expend more ki to add another 1d10 on those attacks.

Is my interpretation of how the discipline works correct?