Hi @steve5528,
1. Technically you would not need ISP support, but it is highly recommended to include it for anything that might go wrong while programming the MCU.
2. You could use LinkFlash, which is a GUI based on LinkServer to flash NXP devices, which is based on command line. If you have the latest version of MCUXpresso installed (v24.12.148), you should also have LinkFlash v24.12.21 installed already.
BR,
Edwin.