Is there a limit to the amount of function buttons that I can show?
No, you can choose to show as many as you want?
Can I hide the Functions or Columns dropdown?
Not currently but these options will be available in a future release.
Can I hide or minimise the Dashboard?
Yes, you can do both. To minimise the dashboard click the small arrow in the top left of the first toolbar (and click again to maximise). To hide altogether choose the appropriate option from the column header menu.