Before the Romans conquered Hispania the region was colonized by diverse peoples. You have Carthaginians bringing in their pantheon, you had Greek colonies and their faith, but the region was inhabited by various tribes of Celt-Iberian decent, because celts migrated there and interbred with the Iberians inbetween 700 and 500 bce. The Celts brought with them Druidism, which proved popular. While certainly not the exact same strain as, say Gallic or British druidism, it was similar enough. The Basque people had a faith centered on a goddess named Mari. Alas, close to nothing is known of the Iberian faith.

You'll be hard pressed to find any traces of of any of those faiths in Spain or Portugal today. The Middle Ages and the Renaissance did a fine job of eradicating paganism. There is likely to be a person every here or there that believe in the Druidic Gods (I know a druid here in the States, for example) but not because a small group managed to hold on to their faith through the millennia.

EDIT: I found this read on the topic. It's not too long. http://libro.uca.edu/mckenna/pagan1.htm

About the bonus question, you can find traces of the pre-christian religions in the folklor and miths of northern Spain, specially in Asturias and Cantabria. It's easy to find plenty of tales and miths which have a celtic and pagan roman origin together to miths from pagan germanic (visigoth) origin. They are just folklor and etnology and at the present time they have no religious meaning for anybody apart from a few neo-pagans. The article in the english wikipedia about cantabrian mythology explain more about these miths if you are curious. I hope I helped you.