What features are available in Japanese to express politeness and social relationships?

Many. Not only in vocabulary & grammar, but even certain manner of speech is required or forbidden on account of politeness, informally (eg can't say "you", must construct sentences through implied references, somehow learn their name & rank or just the title in some cases, like customer). Seek keigo for an introduction, some debated in forums, reliable rules seem fairly difficult to find. Could try to follow the local custom and err, but might not be corrected out of politeness.
- Titles (san, sama, kun etc).
- Verbs have plain and polite forms.
- Uchi-soto, using polite form when speaking with someone outside one of your circles.
- Speaking to or about a person is a factor.
- Gender difference, beside personal pronouns women are expected to express more formally, "ladylike" basically. Maybe less crucial in modern times & settings, however.