I want to try all that I see on this page on my MBWE. I know it's a good practice to backup everything before trying. But is it absolutely necessary? Does the new software interefere with the DATA partition or can I try not to backup? The thing is I haver 250 G of data and that would take sometime to Backup and another drive which I don't have right now
In the description section you say that "I want to install linux on the MBWE", and then in the body of your message you say "I want to try all that I see on this page on my MBWE". These are 2 different things (your MBWE already comes with Linux on it).
The short answer is: either way, back up your data. If you don't have time or if you don't have a spare drive, then don't fiddle with your MBWE - chances that you will not get it right from the first time, are very high, no matter what you try to achieve (install Lenny or just ipkg's).
Just a friendly advice.