2. They were relatives, but the Celtic kingdom of Tylis was an independent entity, not controlled by the Galatians. IIRC at EB's starting date Galatia had an alliance with Bythinia, so you could give them the latter province.
3. Did they come back? AFAIK the Galatians settled quite happily in Egypt. Similarly, I am not sure that Galatians actually served in phalanx units.
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