Hikaru no Go manga vs anime

[neoEIN]

I read that Sai left Hikaru at volume 15.

I've also seen the HnG spring special and am wondering about the Hokuto North Star Cup tournament. Is it a great arc?

Does the manga contain any Go lesson?

I really like HnG anime so is it worth to get the HnG manga?

BTW I'm watchiing HxH TV at the moment. It's another fantastic series. Is the manga better too (atleast covers the HxH G I final)?

Thanks.