Fill from the drain plug hole hippie. Squeeze the lube in until it comes out the vent plug hole. When it does, put the vent plug in and then the drain plug. And leave the neigbor alone.
I second the pump suggestion. The end is threaded and threads right into the fill hole. It keeps the whole process MUCH more clean. I bought one a few years back and refuse to use those grease tubes anymore. Just gotta get the pint bottles to attach the pump to
Yeah. The "Type C" designation is a bit of a tricky subject since I guess it became "OMC Premium Blend" which is very thin and I don't like it on those gearcases. The preferred oil is "OMC Hi Vis" which is a normal ~ 90 weight outboard gearcase oil.
But usually when you pick up a bottle of any other brand 90 weight gearcase lube it'll say "For where Type C fluid is recommended". So the answer is yes.
The motor must be in the upright position when filling for it to trap the correct amount of air. Should take on about 400ml.