RE: dell latitude E5440 dark screen?
Apple has gone to USB-C/Thunderbolt, so an adapter is required for standard USB.
The Air is an older design and still has two standard USB 3.0 ports.
With any Macbook, carefully consider the cost of repairs when buying - EVERYTHING, including the storage drive and memory is aboard the mainboard/main logic board, so just about any conceivable repair inside means a mainboard replacement - which on a Macbook/Air/etc. will cost upward or over $1K.