Fulliautomatix is taken from the phrase "fully automatic".
Fully automatic is a description given to a fully automatic gun - a firearm that automatically ejects each fired cartridge case and loads each subsequent new one as you squeeze the trigger. So maybe the name is meant to suggest the character's efficiency with his blacksmith's hammer, ie: beating metal (or Romans) with the speed of a machine gun.
In the original French, his name is Cétautomatix ("c'est automatique", meaning "it is automatic"), so has a similar meaning (unlike some translated Asterix character's names which changed completely).
Fully automatic can also refer to a car with a fully automatic gear shift system, as opposed to manual. I think in the early days of motoring, village blacksmiths often branched out into car repair and local car hire work (I think I've picked that up from old books and films) so I have wondered if the name was meant to refer to vehicle repair work. However, I don't think Fulliautomatix does much chariot repair work in the books, so this meaning seems less likely than the gun one.
According to Wikipedia, his father is mentioned in one of the books, and was called Semiautomatix, which also suggests the name Fulliautomatix is meant to be firearms related.
I don't speak Spanish, but I'm pretty sure Pepe is pronounced Peppay (with the stress on the first syllable).
Hope that helps! | 
