Can I read this without reading the original shaman king? I watched the original, but I can't really remember anything but the basic premise and the ending.
No, the anime greatly deviates from the manga in the second half so you'd be lost.
Yeah I saw how the anime was only 64 episodes and the manga was 32 volumes, so I thought it might not cover everything.
No. Make sure you read the original (including the Kang Zeng Bang ending) before starting Flowers.
There was a sequel?
Yup and it is amesballs