The best way to communicate is via slack. Phone numbers have also been exchanged for more urgent matters
It will be expected for team members to notify eachother (perferably via the group channel in slack) as soon as they realize that they will be late. If someone is late without notice, the group will wait for ~10 minutes before starting the meeting.
If a person does not respond to a question within a resonable amount of time (reasonable is to be defined by the asker when stating when the answer is needed by) then the rest of the group has the ability to make the decision without him.
Generaly, as soon as possible. It won't be frowned upon to express doubt about meeting a deadline early, as doing so might prompt a change of strategy that could avoid a problem. Whenever possible, however, 24 hrs notice should be given.
As a general rule, we will try to follow airbnb's style guidlines which can be found here: https://github.com/airbnb/javascript