As a novice flying for the first time to BA, I have few questions (for now).
I'm flying Lufthansa LUX-FRA-EZE business class.
Firstly is it worth thinking about paying for an upgrade to First?
Secondly, on the return flight the schedule has changed, and I have a 6 hour wait in FRA.
Do I have access to a business lounge in Frankfurt?
Thirdly, I wil soon have to think about book a hotel in BA for a few nights.
I've read (I think) that it best to book (e.g. Booking) a room and only pay on arrival in € or $.
Thus I have would have the option to pay in peso or use my European CC.
Any advice would be much welcomed.

Finally any advice about finding a personal guide for the city for a day or two?