Hi Debbie
I've not been to this part of Spain before, but like you one of my main reason for picking the holiday is the visit to the Alhambra Palace.
I've not booked the Gibraltar trip, but would aim to go if the border situation is resolved. If I miss out, I'm not too worried to be honest, as there are loads of other things to do within a reasonable distance of Mijas.
Hope you get someone to reply to your "taxi sharing" request.
See you at Christmas.
Stuart