If I want to buy a second car but not drive it all year, do I have to have plates and insurance for all year? Thank you

I presume that this is a seasonal car which will not be driven in the winter. If this is true, you can turn in the plates to take the vehicle off the road for the winter. This will allow you to take the liability insurance off the vehicle. If ypu have a lien on the vehicle you will be required to keep certain insurancelike fire and theft, which you may want to maintain anyway while the vehicle is off the road.

Stored in your garage or covered in your yard . Otherwise if you have it just sitting there you cannot have a vehicle with no plates in view that's why you cover it or store it in your garage. I would call the DMV

I would assume yes to both. Supposedly someone hit your parked vehicle even when you're not driving it... then what? I would just suggest getting lower limits and rating the vehicle as pleasure since you will not be driving it that much