We strongly encourage employees to keep discussions in 'public' slack rooms rather than private messages. This can be noisy but allows for inclusivity. Team members are free to choose which channels to join and are encouraged configure alerting to manage the noise. Only takes a few minutes to set up.
Performance needs to be measured by work output rather than time in the office, but companies should be doing that regardless.
Face-to-face on-boarding and intros to the team are preferable so we would fly in new-hires wherever possible for the first couple weeks. Beneficial but not required.