Hi Coco, I don't know any details of the rules for obtaining residencia, all I know is that they have been changed slightly over the past few months. At one time you had to provide proof of your income and or savings in order to prove that you would not be a burden to the state.Now, as I understand it, you no longer have to do this. You have to apply for residencia if you intend living in Portugal for longer than 180 days, though hardly anyone that I know of has actually done so.
The SEF (Serviço de Estrangeiros e Fronteiras) has a website from which it is supposed to be possible to download the application forms but I have made several attempts at this and have been unable to get that bit of it to work.
If anyone out there has any recent experiences of obtaining residencia, it would be great to hear from you.