I have moved mine twice: once in spring, once in fall. It was a smaller plant the first time (fall). I don't remember noticing a taproot... I did take care to keep it well watered. Since hibiscus are tropicals, I cannot imagine that it would suffer badly from your heat. Definitely mulch, as mxk said, and move it into good soil. Personally, if you are a conscientious one about aftercare, I'd move it now to give those roots maximum time to re-establish. I'd like to know how to propagate them too. Mine is Krown Jewels and I love it.

Only if you can dig it up losing abolutely no soil from the root ball. If any soil falls away it will be like planting a new bareroot, and in the heat we have at this time of the year, it would be almost certain death. Your water restrictions could be a problem also as you would have to water deeply and often until it got re-established again. If you decide to chance it, cut back the top growth so the roots don't have much to support. It would probably die back anyway.

It may be ok but I would choose a time when the plant is dormant instead. As soon as you see the leaves dried out plus 1-2 weeks, I would do it. Or in Spring before it leafs out. Since the soil freezes where you live, I would not even try in the middle of winter.

Being that it's supposedly hardy to zone 4 and you are in zone 4, you shouldn't have to do anything. But, being that it's the first winter, you might want to try mulching just as extra insurance. Just mound peat moss, loose soil, or compost, or leaves over the base. Maybe cover with burlap or a sheet of newspaper and rocks if you think it might blow away. That would help insulate the root zone for winter. I tried hardy hibiscus two years ago but unfortunately, even with mulching, it didn't survive the winter. It's just as well, since they are so late to come up in spring and apparently bloom late in the season, I am not sure it would be a good match for our climate. Of course I am mostly saying that because I am jealous that I can't grow it, lol. Glen