Q 196 If a corporeal creature that only does touch attacks with their natural appendages, but not damage, suddenly takes levels in monk, do they gain the unarmed damage with the touch attacks too, or do those touch attacks now become regular attacks?
Your question is WAY too generic. It depends on the creature and what the creature is looking to do with their attacks.
For example, if we're talking about a roper here then no, the tendrils will not gain a monk's unarmed damage.
I'm just wondering because I'm reading that a lich can choose whether or not to use a touch attack or its natural weaponry. But what if that lich was a thorciasid? Or a rust monster? Or a cockatrice which has a touch, or a claw? Or maybe it's a demilich. There's a lot of monsters out there that have just touch attacks that do ability damage, or drain, or poison, but they don't do actual physical damage with their natural weapons, and some don't even have claws or bites. So if they were advanced as a monk, or had a monk's belt on them, would they gain that unarmed damage to their strikes?
If they attacked as a normal attack and not a touch attack yes.
It's not that simple, it's different for each of the monsters.
For the lich, the touch attack functions in a lot of ways like a spell, so you can deliver it with an unarmed strike and the paralysis just rides along.
For the Rust Monster and the Roper, their touch attacks are delivered by what amounts to a unique natural weapon. These touch attacks do
not gain the benefit's of unarmed strike damage.
For the Cockatrice, the petrification is explicitly tied to it's bite attack. It can never be delivered as a touch attack, and does not trigger on any other attack (even other natural weapons or unarmed strikes).