Informal meetings are a terrific idea – and no, you don’t need an agenda or minutes.
You can use them to decide on what should be on the agenda of the next meeting or to have a relaxed chat with a resident who has raised an issue. A lot of good work can be done, just as long as you remember that decisions made need to be formalised at some point, via a properly constituted meeting with agendas and minutes.
And do it openly, otherwise someone will accuse you of having secret meetings with sinister intent.