Land deeds, and Birth records...

In my family there are various stories of how ancestors had much land and cattle, and my grandfathers talk about their ancestors' land deeds on property (los papeles de los terrenos), or even sometimes on houses (papeles de la casa). I was wondering if one could acquire copies of these deeds, probably from the government building at the municipal seat?

And also in official birth records, not baptisms, parent's signatures are on them. Is there a way to get a copy of these too? I have been intrigued to know that my great-grandfather Fabián Castro signed his name on my grandfather's original birth record. How long ago were these goverment records required?

Thanks,
Valente.