2x Crop Factor = Other Changes Too?

So! On cameras that use Micro 4/3 lenses, I'm trying to wrap my head around the 2x crop factor, when mounting non-Micro 4/3 stuff. (I'm trying to find some cheaper low-light lenses, because there still don't seem to be any official ones from Panasonic/Olympus. Everything is around or over $500, and I just need something that takes good photos/video (manual focus is fine), to hold me for a short time.)

A YouTube video said that a Canon 50mm F1.2 becomes a 100mm F2.4. Is that change in F-number correct? (at least in equivalent light value?) In that case, it would seem that we've got some loss of light to think about, but, at the same time, the "zoom" that occurs because of the 2x crop must make the bokeh size massive. (right?)

So, before I proceed with buying anything, I need to understand exactly what's going to happen if I use a non-Micro 4/3 lens on a GH1, GH2, or, later on, GH3. So far, I've got:
1) The zoom doubles. (enjoy free zoom, but forget wide angle anything)

2) You lose 50% of your light. (F1.2 becomes F2.4, etc... Or is it more than a 50% loss? I remember reading that the difference between F1 and F2 is not actually 100%, because it's logarithmic, or a ratio, or something very bizarre.)
3) You gain massive bokeh.

Anything else?
Thanks!

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