Music player. There are 24 tracks now. In the Sound panel you can go back, pause, skip and pick any song you want. If you like it, turn on "On-screen player" and a tiny player sits on the bar, with the song name scrolling.
The DLC hat is really yours. The pristine Pirate Tricorne from the Pirate's Pack now goes to your Steam inventory. Keep it, trade it or sell it on the Market, your call. Just open the game with Steam running.
What's new on launch. After each update, a small window shows a summary of what changed. Close it, or tell it not to show again until the next one.