Yes, there are two, upstream (or front) air/fuel sensors and two, downstream (or rear) O2 sensors. Bank 1 is the cylinder bank that starts with #1 cylinder. For the VQ engine, it'll be the right, or passenger side, bank on a RWD vehicle like a Pathfinder or the rear bank, along the firewall, on a car like a Maxima.
I've never tried the manual reset method as I've always had a scantool that could do it, but it's worth a try!
If looking for an air/fuel sensor to purchase, I would check with Rockauto.com first and see if they have one by NTK (it's the same company as NGK) or Denso. Both of these are good brands and OEM suppliers to Asian based manufacturers. If you want a site for genuine Nissan parts, try one of these:
www.1stAAANissanParts.com
www.CourtesyParts.com
www.NissanPartsZone.com