By Car: Tokyo - Alpine Route - Shirakawago

Good Day Road Trippers!

Could I please get your advice on this trip I'm planning.
Am really hopping for useful advice as this is the first time I'm planning such a long road trip.
I've read countless articles online and the worst part is that I'm getting myself really confused.
Hence, I really hope I could garner some of your kind help.

Some background:
- Looking to travel from 18 to 22 April 2018 (5 day trip)
- My hubby and I will be bringing our 4 elderly parents with us on this trip.
- Hence, we will not be taking shinkansen, trains etc.
- We want to have minimal transport changes so that they will not be too tired.
- We will be driving from Tokyo - Alpine Route - (Shirakawago/ Takayama - if time/ route permits) - back to Tokyo

1. Anyone done a road trip of this distance before? Would you be so kind to share your itinerary or experience?

2. If we are going by this route [Tokyo - Alpine Route - (Shirakawago/ Takayama - if time/ route permits) - Tokyo] which are the sights you would highly recommend that we visit? That's provided this suggested route is do-able. Or would you have other suggestions?

3. For a 5 day trip, where would you suggest we should be staying for the night? Any recommended hotel or ryokans? (Which towns to stop-over for a stay)

4. Understand that we cannot drive to the snow wall and we may have to back track to get our car. Would anyone have the best route we should take (bearing in mind we have our parents with us) so that we can backtrack to get our car? How long would that take too?

5. We love the Japanese rest-stops along the highway, which are the ones you would recommend that we stop by during our drive?

6. Any local must buy / try delicacies you would recommend along the route?

Thank you so so much!

Really appreciate all your kind advice and suggestions!