gestalt artificer what should the second class be?

[Tokiko Mima]

Warlock would be entertaining. You would have a fun item creation synergy and access to all divine spells, and your mode of attack leaves your hands empty so you can use any magic item you want. Plus you could easily re-flavor Eldritch Blast to be a Ray/Laser gun.

Also: would it be possible for Factotum to enter Ruby Knight Vindicator to reap additional swift actions as well (and abuse Rod of Quicken)?

No, unless you have a different wording available Quicken Spell can only be used once a round in any case.