The Dragon Oracle Mystery gives True Seeing as a bonus spell at level 14, which is normally a 5th level spell for Oracles.
The Dream / Haunted / Rebirth / Self-Perfection Psychic Disciplines gives Ethereal Jaunt at level 14, which is normally a 6th level spell for Psychics.
What spell level is it when they get it? What happens if they have already chosen it as a spell known? Do they then have a lower-level version in addition to the bonus spell?
This might have been asked before, but I'm unable to find anything coherent with the search function, so sorry if it is obvious or intuitive.
Highest spell you can cast at that level, or the normal level you can cast that spell if it's on your list, whichever is lower. This isn't anything new, since some cleric domains do the same, and in fact there is a recent bloodline for sorcerers that grant Sunbeam really, really early, but I'm not sure what it's name is.
If you already know the spell, nothing changes, you just get the spell from your bloodline and you need to retrain the spell known from your normal choices or wait for the ability to swap them out naturally like spontaneous casters already can do.
Highest spell you can cast at that level, or the normal level you can cast that spell if it's on your list, whichever is lower.
That is what I'm thinking as well, and makes sense. Do you have a source for that statement, though? I would love to have something concise to refer to beyond a forum post!
I can't find anything specific to oracles or sorcerers, no, but I can list what it says for cleric domains
If a domain spell is not on the cleric spell list, a cleric can prepare it only in her domain spell slot. Domain spells cannot be used to cast spells spontaneously.
So, for a cleric they can prepare a spell already on their list as normal or with their domain slot (which could be higher or lower). Since true seeing is already on the oracle spell list, presumably that works the same and you can just cast the spell as a 5th level spell. Remember, it's a bonus spell known in addition with all your other spells, and that hasn't changed, so if it's already on your list you basically just get it as an oracle spell as normal. It's when it's not normally on your list that the spell is probably at a higher level.