Yep, that's the oil drain line. Just did this myself on my 8.1. Liquid wrench and a BIG wrench should get it. My plug had been replaced with a steel one that was all rusted, but it still came out. Replaced it with a new brass one. I changed the oil with Rotella, had to go to O'Riellys to get it. As for the spark plugs, you don't need a torque wrench, but it's always good to gap them correctly.
Also, on a side note, you need to flip your ballast pumps while you are in there. The brass pumps need to be on the bottom, so when they start leaking, they don't take out the pump all together. When you flip them, you also have to take the brass pump part loose(2 screws) and rotate it 180 degrees, and you don't have to do any rewiring. I went the extra little bit and polished them and put the green impellers in them also. Have fun!
2005 X45 - L18