.... due to the lack of support from cocoon I havent been able to create gdpr compliance for many of my updated games.
they are not supposed to give u support for the gdpr compliance form you want to build for your own business.
as for the compatibility, i only tested for 5 to 7 and worked good for me. it's just better than C2 that's all i can say. but you won't have the same custom community plugins, you might find others that are similar to older ones but you will be missing a lot of r0j0s plugins and other good stuff.
no doesn't include the gdpr consent form, it will never do that, as the gdpr consent isn't the same for everyone.
yes the exporter you can directly compile with C3. signed and unsigned.