What operating systems and experiences you have, if you haven't already listed it in your introductory message on the sign-up task.
Traditionally windows but am fairly comfortable with the basics of Linux, and will be using my ubuntu laptop for anything to do with Lernanta. I just find that some of the hoops you have to go through with Windows to be a bit painful. I've been working on straight html/css websites since about 2000, and Drupal for about 7 years. I can work both front and backend tasks, at least with Drupal. I do have version control experience having used cvs, svn and a bit with bzr. Never worked in python and have very little git experience. I'm working through a google python course at the moment: http://code.google.com/edu/languages/google-python-class/index.html
Is giving a week to each of the tasks except for coding good at one week?
Seems reasonable.
Also, how do you define open source? If you have good links, that's great. If you have experience, please share it. What are its strengths and weaknesses? Especially from the viewpoint of someone new?
Like Julia, I'm also part of the Drupal community, and the community around Drupal always astounds me - how much it has grown and how much it has accomplished. So I'd cite this as one area of strength for many open source projects. Weaknesses: there is often a lack (or shortage) of paid support options for open source projects, and while developers can fix things themselves, non-developers have to wait around for others to fix issues, and it can take a while - so I'd say it favours the more technically inclined. Those with a less technical background often find it difficult to use open source tools, to learn, to participate or contribute.
There are some useful lessons on working with an open source community in this blog from one of the team that was working on the Drupal.org redesign: http://www.disambiguity.com/?s=drupal If you have time, you may want to start round about page 14 and move to the first page to follow her journey chronologically. In this post she talks about how and this one about social skills required when working within an open source community. I think I've gone off on a tangent now ;-)