First some background. When you attempt to touch someone with a spell, you are considered armed:
Touching an opponent with a touch spell is considered to be an armed attack and therefore does not provoke attacks of opportunity.
You can also discharge the spell with an unarmed strike, but this does provoke an AoO:
you may make a normal unarmed attack (or an attack with a natural weapon) while holding a charge. In this case, you aren't considered armed and you provoke attacks of opportunity as normal for the attack. If your unarmed attack or natural weapon attack normally doesn't provoke attacks of opportunity, neither does this attack.
So if you have some way of avoiding the normal AoO an unarmed strike provokes, it will let you avoid it here.
"With this, would striking someone with (spiked) gauntlets be considered "touching" him?"
Sadly, spiked gauntlets are not such a way; they are basically a weapon (the spikes) attached to your gauntlet. Contrast that with regular gauntlets, which simply modify your unarmed strike, and are classified as such in the list of weapons.
That said, it's a reasonable thing to bring up to your DM as a house rule. Your other options are to take the feat unarmed strike, or to somehow gain natural attacks.
"When I learn, as a druid, to cast spells while being in wild shape, can I attack an enemy using Produce Flame with a natural attack?"
Yes, this is covered by the rules I've quoted above. A natural weapon doesn't normally provoke, so neither would using it in conjunction with spells like produce flame.
Flurry of Blows modifies your full-attack
It adds additional attacks, and applies a penalty. It is otherwise a normal full-attack like any other.
This means you may use any weapon you have available for any given attack. If you are holding two weapons, you can use one or the other for each attack you’d normally have.
Note that this is exactly the same as when you don’t use Flurry of Blows. If you have multiple attacks for whatever reason (BAB +6 or higher, the haste spell, whatever), you can use any weapon you have available for any given attack as you please.
On the flip side, you do not have any more attacks, normally, than you would with a single weapon. You simply get the attacks you would otherwise have. Those can be the ordinary attacks of your full-attack, or extra attacks from Flurry of Blows, or whatever. Simply having two weapons does not give you extra attacks.
To get extra attacks, you have to use the Two-Weapon Fighting combat option (and then you are subject to its penalties and restrictions). In particular, Two-Weapon Fighting is an exception to this “any weapon for any attack” bit. Note that this is more than just having two weapons; you have to actually choose to use Two-Weapon Fighting, or none of the following applies. When you do choose to use Two-Weapon Fighting, it changes your full-attack (much as Flurry of Blows does): it grants an extra attack and applies a penalty, and it also applies a special restriction on which weapon you can use for which attack: specifically, your bonus attack from Two-Weapon Fighting has to be a different weapon than the one you are otherwise using.
Furthermore, under Pathfinder rules, Flurry of Blows is Two-Weapon Fighting (except it doesn’t actually require you to use two weapons). As such, the idea is you cannot use it and Two-Weapon Fighting at the same time. If this is the case, there is absolutely zero benefit to having two weapons, except I guess the ability to pick which one you want. You’re better off with a more-powerful single weapon than splitting your wealth between two.
Unfortunately, the rules here are notoriously vague and have required numerous amendments, explanations, Paizo contradicting themselves several times, and finally overruling previous rules entirely because they never made sense. This is actually one of the most famous fiascoes in Pathfinder history, and the rules are left a mess as a result. I suggest just returning to the 3.5 rules, before all this started: Flurry of Blows and Two-Weapon Fighting are completely separate things, combine them if you want (taking even more penalties and gaining even more attacks). This is still a bad idea, since it is a very weak option, but at least the rules are clear, make sense, and there’s actually, theoretically, a benefit to dual-wielding as a monk.
Best Answer
It's not an endless loop
Combat on Attack on Unarmed Strike says, "An unarmed character can’t take attacks of opportunity (but see 'Armed' Unarmed Attacks, below)." "Armed" Unarmed Attacks says
Thus when Alice—who lacks the feat Improved Unarmed Strike—makes an attack with her unarmed strike against Bob, Alice provokes an attack of opportunity from Bob. But Bob—who also lacks the feat Improved Unarmed Strike—can't make attacks of opportunity with his own normal unarmed strike. Were Bob to possess the feat Improved Unarmed Strike—or employ his dagger—, he'd make his attack of opportunity normally with that appropriate weapon due to Alice's attack and wouldn't himself provoke.
Despite both wielding daggers, wielding a weapon doesn't obviate the attack of opportunity provoked by attacking with a normal unarmed strike nor does wielding a dagger allow a combatant to threaten with the combatant's normal unarmed strike. As per Attacks of Opportunity on Threatened Squares: "If you’re unarmed, you don’t normally threaten any squares and thus can’t make attacks of opportunity." When making a normal unarmed strike, both Bob and Alice are unarmed.
(Note that also both Bob and Alice would both have to possess the feat Combat Reflexes or something similar to even make multiple attacks of opportunity in a round, usually eliminating the possibility of this situation becoming an endless loop that way, too.)