Re: stupid questions but just making sure?
first you get the O ring seals, that go on the drain and vent plugs, the 2 straight slot screws (NEVER remove the phillips screw). the reason is you need them to put on when reinserting the plugs. this is the #1 place for water to intrude into the lower unit.
remove bottom drain plug, pan under motor, remove vent upper plug, while waiting for the oil to drain, put on new seal.
when drained, you fill from the bottom hole, (they make a pump for this) until the oil is at the level of the vent hole. now install the vent plug, this creates a vacuum, remove the pump, and insert drain plug.
recommended is outboard motor lower unit fluid, 80/90 wt. it has an additive to counter water intrusion.
this should be done every fall, before the first freeze. because if the lower has any water in it, and it freezes, it will crack the lower unit. expensive mistake.