Query on Japanican voucher

http://www.japanican.com/tours/tourdetail.aspx?tc=GMT01TYOOVJOPENTK&af...

There is an offer for 21,000 Yen for a round trip from Tokyo- Kyoto as per link above.

However, I am travelling from Tokyo-Kyoto-Osaka-Tokyo. I will be staying one night in Osaka in Nippobashi.

Should I buy the voucher and pay for the trip to and from Osaka (which is a total of 1390 yen). This is cheaper than buying separate trips from Tokyo-Kyoto-Osaka-Tokyo.

The reason I do not wish to buy a 7 day rail pass because the ticket does not allow me to use the Nozomi trains. There is not much savings even if I purchase the 7 day rail pass. If my method is workable, it will be cheaper to buy the round trip ticket (Tokyo/Kyoto) on Japanican and buy separate tickets for the trip to Osaka.

A few more queries though:
- Does anyone know if the Japanican voucher is valid on Nozomi trains? It is not very clear from the website.
- I will depart for Kyoto on the next day I arrive in Tokyo. I suppose I can only change the voucher and make the seat reservation for the Nozomi on the day I arrive in Tokyo then?
- Has anyone used the Japanican voucher before, and is there anything I should look out for?

Thanks in advance for your input!

Sorry peeps - am wondering if i buy the Japanican voucher from Tokyo-Kyoto-Tokyo, do I need to get out of the station when I arrive at Kyoto from Osaka, and head to the shinkansen entrance on this?