Its okay to clean it with that but i wouldnt soak it for more than an hour because the carb is made out of a composite material and may become brittle. I usually just clean my carb if need be with fresh fuel because that eats up the residue with out harming the carb body.
Couldn't say for certain, but any of these carbs are fairly simple to take apart. Usually for either rotary or slide carbs, taking the idle screw out will let the throttle body come out of the carb. Then it's a matter of taking the needles out and the HSN banjo fitting off.