For a daily driver, always choose the Oppo A37fw Stock ROM . Custom ROMs are only for hobbyists who accept the trade-offs.
Flashing firmware is a high-level procedure. To ensure a successful update without "bricking" your device, follow these steps: Oppo A37fw Stock Rom
No. Stock ROMs are signed. To unlock the bootloader, you need a separate tool or an official unlock code from Oppo (rarely given anymore). For a daily driver, always choose the Oppo A37fw Stock ROM