I think width is pretty standard. Unless you are replacing a very old toilet.
I am not quite sure what you are asking, but this is the round front bowl vs the elongated. There are both styles. This one is only a single flush so you will need to look for a different toilet with a dual flush style.
We don't have much trouble with that. But if you hold flusher down longer will dump more water out of tank in toilet to help flush things down. Hope this helps.
I’ve installed about 10 of them and it’s reliable from 2016 and it’s excellent Couple of things that I did not like is the bolt that comes with a little flimsy but other than that the best efficient toilet bar non
Most plumbers will charge in the range of $200. Some more, some less.
Everything but a good seal and water line.