Just on seats as a point of information for the Aug 22 posts upthread, I have a pure Vueling out and BA ticketed Vueling return to Malaga tomorrow, and noted that the BA booking allows me to to select non-premium seats free (including rows fairly close to the front) but not front row or exit rows.

I also got swapped onto a Vueling service from BA after a cancellation.I believe I don't get lounge access in Malaga as it's not a BA operated lounge. That's a little more irritating than the seating given I wasn't told about the VY substitution (though to be fair I found out pretty much immediately the change was confirmed).