Can I use spells whose target is "creature touched" or "living creature touched" on myself?
It's a two-step definition:
From Getting Started:
Creature: A creature is an active participant in the story or world. This includes PCs, NPCs, and monsters.
So yes, yourself, as a PC, are a Creature.
From Magic - Range
Touch: You must touch a creature or object to affect it.
So as long as you can touch a creature, including yourself, you can affect it with the spell.
Yes. All spells with a range of touch can be cast on yourself if you fulfill the other requirements. In fact, it might be better to say, having a range of touch isn't enough to disqualify you from being affected. The only time this may be a problem is if you are tied up or for some other reason not able to touch your hand to yourself - but in most of these cases you wouldn't be able to cast any spells anyway.
You can automatically touch one friend or use the spell on yourself, but to touch an opponent, you must succeed on an attack roll. SRC
Yes, you can. There are just two things to keep in mind:
- You have to otherwise be a valid target for the spell. You cannot, for example, touch yourself with a spell that targets "Living creature touched" if you are undead.
- Touching is kind of like a somatic component that can't be Stilled. Even though the charge is already in your hand (or however you deliver it), you still have to go through the motion to discharge it. If you can't touch yourself, then you can't touch yourself.