You can use two spaces after a sentence-ending period. As always when writing English, Strunk and White apply. An inline comment is a comment on the same line as a statement. Inline comments should be used sparingly. Inline comments should be separated by at least two spaces from the statement.
Inline comments are unnecessary and in fact distracting if they state the obvious.
All modules should normally have doc strings, and all functions and classes exported by a module should also have doc strings. Such a doc string should document the script's function and command line syntax, environment variables, and files. One-liners are for really obvious cases. They should really fit on one line. Triple quotes are used even though the string fits on one line.