0_0 ...I feel ripped off now.

Even better! Graphics Gale is totally free now. Even the gif export!

Well, it turned out great.  I can't wait for your next one!  

I suggest purchasing Graphics Gale or AseSprite for .gif animations. In Graphics Gale ($20 or so) you don't have to worry about the difficulties of making a decent animation like what you would do in GIMP.

I was doing it as "(30 ms)" with a space, which is fine in the built-in player, but the exporter only parses "(30ms)" without the space.

Nice job!  If this were a game, I'd definitely want to play it! 

As for Gimp, it's great you figured it out.  I use Gimp when on the computer and it's always seemed to put out what I'm going for when changing frame times.  How were you adjusting the milliseconds?  If it doesn't really matter too much to me, I'll just adjust the frame time as a whole when exporting.  If I'm feeling specific, I'll just put a number followed "ms" in parentheses in the Layer name.  I don't know any other way in Gimp.