The land registry
https://land-registry.gr
Short term rental AMA-registration and declaration
https://www.aade.gr/brahyhronia-misthosi-akiniton
If you want to let your house or apartment for less than 90-days per year.
You can get an AMA-registration number, to use with Airbnb or other services.
This Facebook group is great for questions and inspiration.
Building or renovating properties on Corfu