Which O2 sensor bad and where are they located on a 2004 Suzuki XL7

What is your question?

Has trouble starting until 2-3 tries and smells like gas in and out of car while driving. Autozone said needs upstream o2 sensor. They didn't tell me the code or which Bank/Sensor. They sold me Bosch part #15040. Any ideas on location of this sensor on car to replace it, or do I need to go back to Autozone to get the actual code, or Bank/Sensor info to know which one needs replaced? Also recently noticed liquid dripping from under car while sitting idle that seems like gas (and maybe oil mixed with it?). Not coming from gas tank, but more towards front of car like under back seat area. Not dripping enough for gas gauge to go down though. Thank you!

How long has your 2004 Suzuki XL-7 had this problem?

Month