spi flash 16MB not working

Hi

I am currently working with SPI flash memory W25Q128BV and using nuvoton processor of N9H30 series.

I have sample codes but not working correctly, but after erse only one time working properly.

I am having doubt in how to use SPI flash in general , so please give your suggestions.

I have following questions:

1.Can I write multiple times in SPI flash and read content without erasing?

2.Is there any way to erase only few bytes?

3.Can I read and write continuously to store data in multiple locations?

Thanks in Advance

R Sridhar