You might want to punctuate your sentences so we can understand what you are asking. With reference to people, you are either local or you are not. You can't be more local that another. In reference to distance we says: nearer; nearest.

Do you mean to say this in reference to somebody who is very loyal to their locality/hometown? Oddly enough, if the place is a town or a state, we say somebody is "so [name of place]" or that somebody is "the most [name of place] person I know" over here. For instance, if somebody is from New Jersey, acts like they're from New Jersey, and is proud of being from New Jersey, it can be said that they are "the most Jersey" person there is. They embody Jersey (god help them). Of course, this is informal language and you usually only hear this in reference to the big cities, like New York.

I looked up in the dictionary to find the english equivalent of the word for the guy who hangs around often at one place, translating the greek word 'tham'onas'. I found the word 'patron' for that; I never heard this word before :) "Localest" rhymes to my ear as cave era English; I don't think it is a formal superlative form anyway. Instead I'd say : " this guy's figure has been haunting this place forever "; I am not sure if that makes proper sense in English aswell.

It is not acceptable usage to append comparative or superlative suffix to the word 'local.' It is okay to say more local or most local, however, it sounds better to me to substitute the words 'close, closer, closest' in place of 'local, more local, most local.'

There's an expression, I believe it's "the most local of locals" or something along those lines.