re: one out of two, sort of...
I seem to recall a procedure for determining carbon isotope ratios in a simple "desk -top" analytical procedure. But I don't remember anything about it, nor can I provide a link...I'm sure someone is working on it. And that was for dating, don't know how it would do on methane.
As far as the second question goes, chemistry is chemistry, here or there. But is life the same here as (possibly) there? I don't know.