I'm new to Kava and also bought KWK micronised Kava - Pouni Ono, Borogu and Fiji Loa Waka. I can tell you that the nausea is most likely related to the Kava being micronised. The last time I used micronised the nausea was so bad it made me so anxious as to offset the anxiolytic effects I am looking for from Kava! The other product I bought was Kavafield Supreme and there is no nausea other than the sickly feeling I get from the taste.
I created a post looking for advice in masking the Kava taste
http://kavaforums.com/forum/threads/kava-and-taste.10262/
On RT, there are people that swear by its existence and those that believe it's a myth and explained by too low a dose and consuming too soon after food. I think the truth maybe somewhere in between. When I increased dosage and took on an empty stomach I started to feel effects. Your expectations may be too high in looking for psychoactive effects. Also different Kavas produce different effects, some creating a more mind high others a physical body effect