The third is one I'm not familiar with. It is a triangle pointing downwards, with a capital F within it. Is this some fire related symbol,......or does it mean a fuse value or something else?
If there is no fire rating, then are these going to need fire hoods? And would that remain the case if CFL lamps were used (instead of the 50W halogen each light was supplied with/
A capital F in an upside down triangle
Fire rated fittings or fire hoods are only required when breaking a fire barrier between fire compartments. I may be corrected here but I don't think that's the case with your situation as you're living in the top flat so no fire compartment above yours.
Differing lamps won't change the above. It's all down the the fitting itself offering a set fire resistance between fire compartments when an existing fire barrier has been broken (plasterboard ceiling for example).