Tate-Kurobe Alpine Ticket - Shirasagi Course

I am hoping to do the Tateyama Alpine Route, and wish to use the Tateyama Kurobe Alpine Ticket, starting from Nagoya to Toyama, via a stop for two nights in Kanazawa and a night in Toyama. On the return journey, we hope to visit Tsumago and Magome.

Questions:

1. Am I allowed to stop at Kanazawa for 2 nights and then proceed to Toyama? Does this journey has to be the same Shirasagi Ltd Express train, or can it be any JR trains (eg Thunderbird or even local JR trains)?? Do I need to book the reserved seats in Nagoya at the start of the journey for the Kanazawa to Toyama stretch if on the Shirasagi Ltd Exp? Or can I just hop on to any train(s) to Toyama when I have finished my itineraries in Kanazawa?

2. On the return journey, can I transfer (without leaving the station) at Nakatsugawa for a local train to backtrack to and getting off at Nagiso for Tsumago, and return to Nakatsugawa, after visiting Magome, to continue to Nagoya? on the Chuo line.

Thank you.

Am I allowed to stop at Kanazawa for 2 nights and then proceed to Toyama?

No, stop-overs in Kanazawa are not allowed.

Does this journey has to be the same Shirasagi Ltd Express train, or can it be any JR trains (eg Thunderbird or even local JR trains)?

You are supposed to take the Shirasagi all the way from Nagoya to Toyama. Theoretically, I think you are allowed to take local trains, instead.

Do I need to book the reserved seats in Nagoya at the start of the journey for the Kanazawa to Toyama stretch if on the Shirasagi Ltd Exp?

You are not allowed to get off in Kanazawa. You are allowed to make a seat reservation for the Shirasagi, but it is not mandatory. You could also ride in the unreserved car, instead.

On the return journey, can I transfer (without leaving the station) at Nakatsugawa for a local train to backtrack to and getting off at Nagiso for Tsumago, and return to Nakatsugawa, after visiting Magome, to continue to Nagoya? on the Chuo line.

No, backtracking is not allowed!

Note also that the railway line along the Kiso Valley is likely to be out of service for about a month due to a landslide:
http://www.japan-guide.com/e/e6075.html

Since the chuo line is damaged, the ticket to starting from Nagoya is to stop the sale.
I answer for if you want to buy it after the sale of it is resumed.
Indeed, it is not possible to stop off at Kanazawa using the ticket. There is a need to go to Toyama once. The ticket is two split of go and return ticket, a ticket to go is collected at Toyama Station. If you want to go to Kanazawa Station, there is a means to buy a round trip ticket to Kanazawa Station after you get off at Toyama Station. After finishing the itinerary of Kanazawa, you may be able to use the Alpine Kippu of rest after returning to Toyama Station, as long as it is within the validity period.
Similarly, on the chuo line, you will not be able to turn back. You will probably need to be selected as the starting point one of Nakatsugawa Station or Nagiso Station to go to Magome and Tsumago.
Whatever the case may be, the valid period of the ticket is the 8 days, it is necessary to plan the itinerary in that period. If you are going to stay in Magome, there is also a means to return to a highway bus to Nagoya with abandon the ticket.

Thank you for your replies.

Followup question:

Can I get off at Kanazawa (from Nagoya), and then pay a separate ticket to get to Toyama 2 days later? Will the station master let me off at Kanazawa or will this annul the Tate-Kurobe Alpine Ticket ?

thank you.

I was not aware that there are means mentioned you. Instead of stop off at Kanazawa, it's simply, it is means that go to Kanazawa by half of the Alpine ticket, and buy another ticket between Kanazawa Station and Toyama Station may be possible.
However, at this time, the sale of the ticket until it is restarted, you can only choose to buy other tickets.