Confusion about Hori sticks

Hi guys. Im going to buy my first arcade stick soon, and since i don't own a ps4 yet (but surely will in the near future) i decided that to go for the Hori sticks which are ps3/ps4 compatible.

But now, which one of them should i buy? I know there's the HRAP V4 Hayabusa, then on march it will be released the HRAP V4 Hayabusa Kai and some day in the future we'll have a HRAP V5.
In these days i tried to buy a V4 Hayabusa but i couldn't find it anywhere. Amazon doesn't have it, Play Asia doesn't have it, the very Hori website doesn't have it, i didn't find it on ebay either.

It seems i have to wait so why not wait till the V4 Hayabusa Kai will be released? It seems a good idea, but what about the V5? When will it be released? What's its price? And which are tjhe differencies with the V4 Kai?

One last question. I read this article http://shoryuken.com/2015/01/20/hori-real-arcade-pro-v-for-playstation-4-and-playstation-3-now-up-for-pre-order/ where they say that the V5 will be available on march (the same date of the V4 Kai, my confusion is growing), and that's it's possible to preorder it on Amazon Japan. What i need to know is: if i buy the stick from there, will it function on my european PAL ps3?

Thanks.