Oil Drip - Lower Unit

[Three Ts]

There is a small amount of oil oozing out of a small hole on lower unit, left side. What is this hole, and what are similar two holes on right side of lower unit? One seems to have a soft plug down in the hole and the others don't that I can tell. They are small, about 1/8" in diameter.

[boats.net]

There are drain holes in the gearcase, probably need to remove lower unit and check for oil leaks and have it pressure tested.

[Three Ts]

Will I need any type of gasket kit to re-install the lower unit once I remove it?