[tio flaco]

I'm looking for discussion about the article "lo" and how it is recognized (by an English speaker) as a part of speech and its changing definitions. i.e.

the "thing",
Lo bueno, lo unico, lo peor, lo triste, lo malo

or "how" as in, "De lo bonita que es Carmen"?

and finally in idiomatic expressions,
a lo lejos, a lo major, por lo pronto, por lo tanto