A: Technically yes via the Wi-Fi interface, but it is dangerous. One phone call or notification could interrupt the connection. Always use a laptop via Ethernet.
A: In most cases, yes. Firmware updates often revert settings to default. Save your SSID and password before starting. Update Software in ZTE MF296R
A: Your carrier restricts OTA updates. You must manually download the firmware from their website and use Method 1 (Web UI). A: Technically yes via the Wi-Fi interface, but