We arrive at Shanghai Pudong at 22.55, so if you could tell us how to get to West Nanjing Road metro station (we have an accomodation close to this metro station)

You cannot use the metro line 2 to West Nanjing Road. The last train of the line 2 is at around 22:00, so you may need to use other methods.
You may try the airport shuttle bus line 2 to its terminal at Jing'an Temple and then change to a taxi to your hotel.

BTW, your flight land at the airport at 22:55? After you get out of the airport, you may not catch the last bus of line 2, because the last bus is at around 23:03. But do you worry. If you miss that bus, you can take the bus Night Line to reach Middle Zhejiang Road (Yan'an Road, People's Square) Station and then use a taxi to your hotel.