How do you plan on getting to Italy? If you’re using your own transport and don’t mind driving/riding to the circuit then anywhere on the coast between Cattolica and Riccione will leave you a relatively short journey but the traffic will be bad on race day so I’d be more inclined to take the pain and walk there. You’ll find plenty of choice in Misano Adriatico if you book early and it’s going to be just over an hours walk either way.
We took our motorhome when we went and then cycled to the circuit, it was an easy 10 minute ride from the site and we chained them to the perimeter fence. If you’re camping then again, plenty of campsites in Misano but you’ll need to book in advance.
As for grandstands, we watched from Brutapella Gold which was ok, try to pick somewhere with a big screen in viewing range if you can but there aren’t any bad spots so it’s all about what you want to see.
Send a PM to Khulu, he’s been a number of times and always walks to the circuit so he’ll be able to advise on hotels within walking range.