Yes. You can access the spell check feature by choosing Tools, Spellcheck. A spell check dialog box appears; as each misspelled word is found, you can replace it with a word from a list of possible corrections or enter a new correction on your own.
Q2:
It distracts me when words are squiggly-underlined because Writer thinks they're misspelled. Is there a way to turn this off?
A2:
Yes. On the Main toolbar across the top of the application window, you'll see a small button containing the letters ABC over a wavy red line. Clicking this button toggles the spell-as-you-go feature.