Central governments almost never willingly give up territory and tax money. Same here in the U.S. in 1861.
Well, that’s part of their responsibility is to protect the integrity of their borders.
Not sure where people keep getting the idea that succession is an unchallengeable action. Other than a very few notable exceptions, they have been contested for thousands of years.
I mean, good luck to them, but after the celebration comes the civil war. And goodness knows Spain can really put their all into that type of thing.