Drive From Nagoya to Alpine Route in April

We are 4 adults flying in and out to and from Nagoya for 8D/6N. We intend to self drive and want to cover Alpine Route in Mid April 2020 when the snow corridor is opened.
1) Is it feasible to rent a car from Nagoya airport and return car at Dentetsu - Toyama Station?
2) How many types of tourist pass to Alpine route are there? Should we buy the Alpine-Takayama-Matsumoto Area Tourist Pass or is there other pass (as we would have covered Takayama and Shirakawa-Go on our own prior to that before returning our car at Toyama Station).
3) We intend to stay one night up at Hotel Tateyama. Does the tourist pass allow unlimited round trip as we intend to leave our luggages at the hotel in Toyama and just bring hand carry for the overnight stay and we will come back to Toyama and re-rent a car to continue our journey before returning the car at Nagoya Station.
4) Any other alternative way ?
Thanks in advance.

1) Is it feasible to rent a car from Nagoya airport and return car at Dentetsu - Toyama Station?

Certainly. Why not? Note, however, that public transportation is pretty convenient between Nagoya, Takayama, Toyama and Shirakawago.

2) How many types of tourist pass to Alpine route are there? Should we buy the Alpine-Takayama-Matsumoto Area Tourist Pass or is there other pass (as we would have covered Takayama and Shirakawa-Go on our own prior to that before returning our car at Toyama Station).

There are probably dozens, but they combine travel along the Alpine Route with access to the Alpine Route. If you use a car to access the route, then the passes won't apply to you, and using regular tickets would be the way to go.

4) Any other alternative way ?

Do all by public transportation.

Thanks Uji san.
Does that mean it is more economical for me to purchase per trip ticket at each station instead of getting the tourist pass? Do i need to purchase in advance?

Does that mean it is more economical for me to purchase per trip ticket at each station instead of getting the tourist pass?

A round trip by regular ticket between Toyama and Kurobe Dam costs 13,190 yen (https://www.alpen-route.com/en/transport_new/fares.html), which compares to 17,500 yen for the tourist pass. The tourist pass would also cover public transportation between Nagoya, Takayama and Toyama, though.

Do i need to purchase in advance?

No, tickets along the Alpen Route do not need to be purchased in advance.

Please be aware, that there will also be quite high drop-off fees if you rent a car in Nagoya and return it in Toyama. It's going to be at least 10,000 yen, probably more. So you would have at least 20,000 yen for your two drop-off.

Also make sure to figure out expressway fees since you are likely to use one. They can add up and while there are various expressway passes since you are returning the car they would only be valid for each of your rental periods.