Re 1, 2 and 5: gismu are generally neither created nor removed. The change you outline would be the most radical change to gismu space in the history of Lojban. It would invalidate much existing text, and is therefore unlikely to be accepted.
For examples of gismu changes that might considered by the BPFK, see http://www.lojban.org/tiki/BPFK+Section:+gismu+Issues
Fair enough. Nonetheless, having gismu for some languages/cultures/countries, and tying those things together in a single word, pretty much invalidates any claim to cultural neutrality--if the BPFK is serious about this issue, something will have to be done at some point to address that issue.
Re 3, 4 and 6: fu'ivla like this are being created all the time, and is a good thing IMO. But care should be taken to make them as close to any relevant autonyms as possible.
The problem with going straight from autonyms is that we're going to run up against a lot of languages the have sounds which we can't represent in Lojban. Since the ISO codes have, in some sense, already gone through the trouble of putting such things into an ASCII form with largely obvious and transparent replacements for many of the sounds, this seems like a good place to start.
Only the LLG can change the gismu, but anyone can make fu'ivla. I suggest you go the latter route exclusively.
Re 4: it may prove difficult to make a workable mapping from ISO 639-3 codes to fu'ivla. Such a mapping would necessarily be quite opaque, which would hinder adoption. I suggest using fu'ivla based entirely on autonyms. Making good fu'ivla based on autonyms requires some knowledge of the source language, which means that it cannot be done automatically on the basis of a list of autonyms.
I don't really think this would be that difficult. Plus, ISO codes get us one other advantage in terms of recognizability. There cases, for example Finnish, where something like "fin" occurs in pretty much every language's word for Finland/Finnish, EXCEPT for Finnish itself, where it is "suomi." The ISO, rightly I think, uses "fin" for Finnish instead of something like "suo."
Not sure what you mean by “coordinating”. A lot of this can be done on an ad-hoc basis, but requires some quite arcane knowledge on the part of whoever actually coins the word, especially when it comes to fu'ivla.
Yes, this could be done on an ad hoc basis, but then one ends up with a bunch of random words with different forms made by different people at different times. I was just thinking that, by agreeing broadly on a set of criteria and getting the largest languages/countries/whatever out of the way, there would be an internal consistency to it, making it more logical and thus more lojbanic.