Presets are found in your user Library folder. You'll need to open Finder, and click Go, then hold down the Option key to enable "Library" in the menu. Click Library, then follow the path:
Within this folder, you'll find subfolders with all your presets and templates. Copying folder by folder is the best way to make sure you get everything you need. Make sure you keep the presets and templates within the exact same folders on the new machine.
Plugins are best migrated by re-installing.