Short answers, in order: Aspect of Ritual doesn't have to match Aspect/School of spells in the Spellbook; Aspect of Ritual does not need to match Aspect/School of swapped spells; a Spellbook can contain both Celestial and Earth spells if it has enough pages; Spell Swap does not use Meditation and therefor is unaffected by Quicken Meditation.
Longer answers:
The Aspect of a Ritual is irrelevant other than for the purposes of who can cast it and whether Biata react to it; so long as the target is valid, any Aspect Ritual can be placed on any item without issue. (At least from a pure rules perspective; putting a Necromantic Aspect Ritual on something is probably going to cause you some problems In Game if people find out.

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Spell Swap doesn't mention that it requires the Aspect of the Ritual and the Aspect/School of the swapped spells be the same, so it's fairly safe to assume they don't have to match.
A Spellbook is just a normal book, but spells are written in special ink; as long as the physrep you use has enough pages to fit all the spells from both schools, there's no reason you can't put both in one. If it's got enough pages, you can also make it an Alchemy book. Just remember that without Cosmetic Transformation, you cannot scribe spells into a Spellbook that is a Magic Item.
Spell Swap uses a Focus requirement of 60 seconds studying the Spellbook, and does not mention Meditate at all; Meditate is a specific use of the Focus mechanic, but not all things that require Focus require Meditation, and Spell Swap is one of those, which is why the Focus time is stated on the scroll, and also why Quicken Meditation has no effect on it. (You can, however, use the Exchange Spell High Magic ability with Spell Swap to reduce the time to 3 seconds; this interaction is explicitly stated in the description of Exchange Spell.)