Before you check your oil level, tilt it as high as it goes and leave for a few seconds. Then drop it down to a "level" position. Wait a couple of minutes for the oil to drain into the sump.
If your oil level is not midway between the cross hatch pattern on the stick, take a little oil out. (I have a small oil pump.) That way you can watch the oil level closely for awhile. You're right not to want to overfill the oil.
After my first oil change, I switched to Mobil 1 EP which is a superior motor oil. And the Ford Focus 2.0 engine oil filter is the same that is used by all Yamaha 4 stroke engines. Both are available at Walmart.
I use Quicksilver lower unit grease--$9 at Walmart--and I drain it into a Walmart kiddie swimming pool looking for water intrusion and metal shavings.
My entire yearly maintenance is a 30 minute job, and I most often do it at the boat ramp. Sure beats spending $300.