You should join the "Developers" mailing list, and discuss these changes there.http://arduino.cc/mailman/listinfo/developers_arduino.cc
Adding/changing error handling in the Arduino environment is likely to be discussion provoking.
I think there is a general resistance to implementing large parts of a C++ runtime library, for example.
1) Discuss the issue on "developers."2) Create an "issue" at http://code.google.com/p/arduino/issues/3) submit diffs via the issue (so other people could apply it before it is accepted to the official code), and/or via pull request (also somewhat depending on overall complexity of the patch.)
Fighting "management" to get new ideas accepted is certainly one of the less pleasant parts of software development :-(
To set your expectations, changes are typically accepted to Arduino typically happen on the time scale of months, not days or weeks. Yeah, it's slow.