Last year, they limited the number of people with access to the beta site to 5 per team. That doesn't mean that more people can't participate, but it does make it harder for additional people to provide feedback. In both year's I've done it, I don't think any team has had 5 active people providing feedback. I think 5 might be the right number, we had less when we did it.
In the first beta test, we spent all day Saturday and 2 nights a week at the shop. We also spent about an hour a day working from home (reading the forums, coding, documenting, etc). For the second beta test, we did not meet during the evenings, but everything else was about the same. In both cases, beta testing went into early December.
The people who are working on the beta need to be familiar with the robot and the code, ie this isn't a job for rookies. However, rookies are valuable for reviewing the documentation. There are still a lot of problems with the documentation, and I hope FIRST will make that a priority this time.
FIRST hasn't released much about what this beta test will entail, but the documents from
2009 and
2010 are still available. In general, I think very few, if any, of the beta teams met every single one of the expectations.
One of the things that they had both in 2009 and 2010 was porting last year's robot code to the new libraries, with the same functionality it had with the previous code. Depending on how much they've decided to change, this might be trivial, or it might involve starting from scratch. If you don't think your team could do it starting from scratch in around 2 weeks, you might want to focus on your core programming skills, rather then beta testing. It is much easier to re-write something, however, so just because it took 6 weeks of build season plus a month of tweaking to get it right the first time doesn't mean it is that hard to do it the second time.