Applying for a Schengen visa while living in the UK: how to find an appointment, which country to apply to, and how the cascade rule works
The Schengen country to apply to is the one of the main destination; if that cannot be determined, the country of first entry is responsible. Long multiple-entry visas are given in steps: 1 year, 2 years, 5 years. The length can be shortened. Appointment bots are not official.