I think that there should be one person to represent the work their team is doing with the other groups. If there is a manufacturing team and a development team there should be one person to compile everything and distribute it to the other groups. The project manager should make sure that all the teams are communicating with the groups they need to be communicating with.
As for the platform of communication, I think it will vary depending on who you are working with and their situation. There will be times when you work with stakeholders that could be in a different time zone than you. In that case a face to face wouldn’t be the best option and you might be better off with an email or texting if they get to texts faster than emails.