There is a time lag with BOINC from when results are sent in and when they are validated, but joining a team as soon as possible will help minimize any problems. I would guess that the time sent in would have something to do with it. The UD version is more direct, as the team in effect when the workunit is sent in would govern.

Points sent in without a team are lost as team points and only go to the individual. JOIN SOMETHING to help them out. There are many, many teamless members out there. It works like "matching". The same number of points goes to the individual and goes to the team during the time that you are a member of that team.

One can change teams as often as you want, so it is not cast in granite. Old points stay with the old team, and new points go to the new team.

There is a forum team area where several teams post messages among members or to other teams. THAT IS THE ONLY AREA PERMITTED HERE FOR TEAM RECRUITING, so I am trying to give a general answer. Since there are so many teams, ONE active thread per team is permitted.
When it exceeds 500 messages, response time will be a concern. Ask for a lock and start another team thread.
Some of us also have team links in our signatures. If you look at ANY team page, the "Find a team" link on the left has some searching capability where you can look for a team name containing a word, such as "Texas" or "IBM". Since there are already thousands of teams, it is not necessary for every member to start their own team, but you can if you want.