Can I use it with no backlight? And is it easily readable in bright sunlight?
You can experiment since you already have one. Generally, the positive types (lights going through the pixels, like white-on-blue) don't work without backlight. The negatives (reflective. lights got blocked by the pixels) work without backlight.
Or does anyone know of a good, reflective LCD display that is serial-enabled for Arduino?
Parralex (?) has them. and I am sure New Heaven has them too. However, they are generally quite expensive and it makes more sense (and more fun) to program an avr that functions like a serializer.