Second notch on NIC's PCI connector and opinions on a NIC

While trying to find the cheapest, reasonably reliable wireless adapter (dongle or card) for connecting a new build to my family's home network, I ran across this: Rosewill RNX-G300EX IEEE 802.11b/g PCI Wireless Card Up to 54Mbps Data Rates 64/128-Bit WEP, 802.1x, WPA, WPA2, AES, TKIP with 100cm cable external 2 dBi Antenna. I have three questions: First, am I correct in assuming that the "PCI Interface 2.2" it lists is standard for most modern PCI slots (like the ones on the GIGABYTE GA-Z68A-D3H-B3 LGA 1155 Intel Z68 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard I'm considering), which seem to be described only as "PCI slots" even on the manufacturer's specs pages? Second, what is the purpose of the second notch on the front of the connector? It kinda looks like it's placed to allow the card to fit in a PCI-e slot. Lastly, any opinions on the card itself? I'm just looking for something cheap and functional, it doesn't need a higher speed than 54mbps, and that's the first decent-looking one I've seen for $10. The corded antenna won't be a problem to situate.