I received a Grant - how do I categorize this income?

You'll want to create a new account named "Grant" in your chart of accounts if this account isn't already set up. This would be a Miscellaneous Income account. Your tax preparer would likely dig into that account at tax time because some Grants may be taxable income and some may not be taxable. So it's good to have a separate account for Grants set up to easily identify the grants at tax time.