Your questions are very relevant but, unfortunately, I have very little additional information on him. My aunt is the only living ascendant and she generally recalls her grandfather as being from Murcia but does not know if from the City or the Province.
As for his maternal name, I assume that the name was Gurcia but I’m not positive. I found his maternal name on a Census form in Puerto Rico. Acknowledging that the name Gurcia is unusual, I initially assumed that the person who took the Census may have mis-written (longhand writing) the name Garcia as Gurcia. The issue I have with my own theory is that the same Census taker wrote his paternal name as Garcia (where the letter “a” is closed on the top, as it should be) but wrote the maternal name which immediately follows as Gurcia (where the letter “u” is open on the top, as it should be).
I followed the link you sent me (thank you!) and found a baptism record for a male in Murcia born in 1863 with the name Garcia Garcia. I’m guessing this might be him and will try to find additional information on him. Perhaps I can track him on a ship to America in 1882.
Thank you, Lucie, for the information you provided. All the best to you!