I'm curious about that too, I'm also curious as to whether they can cast spells with opposing alignments to them. The class doesn't mention them having alignment casting issues, so can a Good Oracle cast Dread Bolt repeatedly without issue?
Well casting spells with alignment descriptors is an aligned action, so an oracle would need to be mindful of that.
For the deity isue, seems like deity specific spellz I have seen just say the "spellcaster" must follow the deity in question, so an oracle without a deity is out of luck.
In PFS, maybe this is a thing, assuming the character hasn't chosen to specifically worship Issek the Jug Cayden Cailean, or possibly even if they did. (People do get attached to minutiae after all.)
I would rule that as long as the Oracle acts appropriately as to CC's precepts he could have access to the spell. Unlike the majority of an Oracles divine magic, this spell would be contingent upon "keeping the faith".
I'm not sure there are hard rules on this.
Unless I see something to the contrary, the way I rule it is that Oracles can't cast spells restricted to worshiping deities normally as the deity they worship is not necessarily the provider of their spell casting ability.
It's one thing that can help to separate clerics for oracles (oracles for the most part being a better class than cleric).
By the same token, Oracles aren't restricted from casting any sort of alignment based spell because it isn't mentioned in their entry.
The spell in question also is listed for wizards and bardz, how do they get it? The rules I see require the caster to worship the appropriate deity, and worship does not always mean receive spells from.