If you look at the FORUMS at the top and go down to living in Spain, moving to Spain, buying in Spain and so on, you will find every possible question asked and answered on there.
It would be impossible to answer a question on " how much would I need to live" unless we could guess at your lifestyle, whether you run a car, whether you have a pool, how much your commujnity fees and so on are, even down to how much you drink or smoke. Some can live on quite a small amount at 4 or 5 hundred euro a month each whereas others will spend in the thousands.
Whichever way, I wish you the best at moving over. We have thoroughly enjoyed our time here and have no intention of moving but everyone is different As is their spending.