1. Yes. The 2017 MacBook Air's SSD is not soldered and is replaceable. It does however use a proprietary connector. You'll either have to get a compatible SSD from an Apple Service Provider, a 3rd party like OWC or use an adapter with an M.2 SSD. There is a guide available on iFixit.
OWC 1.0TB Aura Pro X2 SSD Compatible with MacBook Air (Mid 2013-2017), and MacBook Pro (Retina, Late 2013 - Mid 2015), and Mac Mini (Late 2014) PCIe NVMe Gen3x4 SSD 1TB 512GB 256GB 128GB 3D TLC NAND Flash Hard Drive SSD Replacement for Macbook Air 2013-2017, Macbook Pro Retina 2013-2015, iMac 2013-2017, Mac Pro 2013, Mac Mini 2014 (1TB)
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