Is there a way to basically hit someone in the face with a charged spell in hand, without provoking an attack of opportunity?
In the core rules it says that you can perform an unarmed strike or natural attack when having a spell charge in hand to discharge the spell upon striking, though when not being shapeshifted or having any feat that gives you a natural attack or improved unarmed strike, this would provoke an attack of opportunity for the guy you want to shove the spell into.
With this, would striking someone with (spiked) gauntlets be considered "touching" him? (Going as far as "removing" the metal on your fingertips?)
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? – The whole idea came from the want to simply smash someone's head in with a fiery fist using that spell, though AoO aren't something I want to provoke.
Best Answer
First some background. When you attempt to touch someone with a spell, you are considered armed:
You can also discharge the spell with an unarmed strike, but this does provoke an AoO:
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.