Craft 3 - Fixing deprecation errors I'm used to writing Twig 1 syntax, and since switching to Craft 3 (which uses Twig 2) I keep getting lots of deprecation errors in the control panel.

Is there any reference material that provides the Twig syntax I should be using instead for Craft 3 sites?
Yes, with the launch of Craft 3, Pixel and Tonic have provided some documentation on switching from Craft 2 syntax to Craft 3.