Granted there are several different schools of thought about early Celtic history, but that mostly concentrates on whether they originated in central europe (the traditional view) or in the region of the Black Sea (the more biblical view). Aside from that point, the field of Celtic history is really quite well developed and there is much consensus about many aspects.
It strikes me that you would be much happier (and you don't sound happy at all) if you boned up a little on the subject of the Celts before carrying on this blizzard of posts about Celtic language. Basics come first, then perhaps later one can be an expert.
Cordially...