Yes, the valve seals can be replaced with the head still in place. Need to remove the cams and the valve shims, then pressurize each cylinder with compressed air and you can pull the valve springs and keepers out from the top with the right tools.
The oil level light is a sensor in the side of the block that may or may not be accurately reading oil level.
Many of us have taken it out, installed a new o ring, cleaned up the sensor and the issue with the light coming on randomly goes away.
In other cases, like mine, that light still...