Undeveloped response for item 4.

To my knowledge people form close bonds in two ways. First: sharing things which make them feel vulnerable. Those things you feel as though you need to trust someone a lot before you can tell them. Paradoxically, telling people these things creates trust in them and encourages friendship. Just don't give too much too quickly. Plan: create exercises where people are directed in sharing intimate things about themselves, perform these at meetups.

Second: Jointly overcoming adversity or challenge. When a new member joins a meetup, take them to do things you are good at and help them become good at it too. Then switch roles.