One to three weeks. Nord and RPM mesh coils sit at the friendly end; high-power TFV tank coils burn brighter and shorter. Sweetened liquids are the main coil killer whatever the family, so if yours die weekly, try a less syrupy juice before blaming the hardware.
If your kit is a Nord 4 or Nord 5 running the RPM-style pod, yes; that cross-compatibility is deliberate and printed on the pod. The original Nord and Nord 2 take Nord-family coils instead. Match the pod, not the device name.
Prime it: a few drops directly on the cotton ports, then five minutes standing in a filled pod or tank before the first fire. On adjustable kits, start at the bottom of the printed wattage range and work up. Done that way, a coil that lasted five days starts lasting a fortnight.
Almost always. Reseat the coil and pod, wipe the contacts, and if the message survives, fit a fresh coil. Our SMOK brand page covers the full troubleshooting drill.