New here - a residence question...

Hi. I wonder whether someone could help with a question I have...

I am a national of an EU country. I have been living in Spain since June 2012. I applied in April 2012, and received, an NIE. I am living in a house owned by my partner, who has an NIE from the same date. My aim is to live permanently in Spain.

I applied for my NIE on form Ex-15. I've now spotted a form Ex-18, used for residence. Do I need to complete this form and submit it where I applied for my NIE?

In other words, to be as fully invested in life here in Spain, is there anything further I need to do (apart from empadronamiento, which I plan to sort out in the next few weeks).

I am retired, but under official retirement age in terms of my 'home' country. If I need to fill in form Ex-18, what accompanying documentation will I need?

Thanks!