The masthead I believe. He's comparing himself to a part of a ship. He compares his skin to the wood.
"Of" is a preposition in the phrase "Of studying" and "until" is another, as well as "to" in the phrase "to college" so there are 3 in that sentence.
The last answer sets the most formal tone; "Hello! I was very pleased to meet you at the party last week." the rest are very casual.
The narrator is invited to dinner as an anniversary of sorts that happened a long time ago, where he announced that he built a time machine. And then he arrives dirty and rugged beginning to tell the guests his story
