Ribbon device info
I believe, as previously mentioned, that the ribbon device can still be used by somone who has lost their symbiont, because they retain the protein structure of that symbiont in their blood, and also remember how to use the device through the retained memories of the symbiont.
A guess as to how the device is powered; since I don't believe it has ever been mentioned (as far as I recall), it seems logical that the ribbon device would draw on the user's own body energy. The human body puts out a large amount of heat and electrical energy, and if you take into account the power that some religions/philosophies place on thought, the user could simply
will the device to do as he wants. Alternatively, it could well have a small internal power source.
As for why they look so "chunky and kinda ugly compared to the one Ra used in the movie" -- well, why do Apophis' serpent guards' uniforms look so chunky and kinda ugly compared to Ra's guards' in the movie? Looking especially at the headsets, which in SG-1 hinge back in a decidedly incongruous manner, the ones in the movie that (with the benefit of some nifty computer graphics) slid all the way into the shoulder plates of the uniform were a darn sight better. One word: money. It's just too expensive to have effects like the movie headsets in a television series; as it is, SG-1 has extremely wowable special effects, but I suspect that this particular one was extremely difficult to produce, due to synching with the actor's movement. While a chunkier ribbon device probably wouldn't cost much less, on the other hand, it was probably done to maintain a consistency in the trend Apophis' and other Goa'uld equipment seems to have in the series towards "regression" -- ie, Ra had the bestestist* tech in the movie, and all the other system lords et al are somewhat behind. If this were not the reason, I can't think of any other, except perhaps that they lost the movie prop and had to make another one out of metal wire on the spur of the moment
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*
bestestist adj. The state of being the best, above the bestest, which in turn is above the best. (Compare to good, better, best.)
Please don't take this seriously; "bestest" and "bestestist" are
not words except in my own demented mind.