Kim, the area at the end of the Breaksea Spit is an almost fabled location but it only fires at very specific times. It's a hell of a journey out there and not for the uninitiated as it can get really nasty out there.
The reason why you see very little discussion on blanks is very simple - there are bugger all blanks out there that are suitable and what is available is not of the same quality as what you will find off the shelf from the top manufacturers. Over the years, we've seen guys using a variety of blanks for popping. Calstar have a couple of blanks that are ok but the guys nearly all end up moving to specialised popping rods in the end if they continue in the sport.
the Keyolhu is a decent rod but if you have decided that you want to buy a GT rod, do your research on what suits you. I have written up a rough guide on the issues for you to think about.
http://www.gtpopping.com/forum/index.php?topic=1374.0if you get a decent blank, proper MNSG or ICMNSG guides and get a rod-maker to build it up, you are probably better off IMHO if you buy a second hand stick. PLease note you may not be comparing apples with apples - the rod that is being made up for you may be significantly cheaper because it isn't being constructed with SiC guides like the MNSG. It is not recommended that you compromise on the guides for GT fishing. I have also seen a number of custom built popping rods where the rod-makers just don't understand the sport. We see runner and tip sizes like 12 where you need 16.
You don't have to spend $1000 on a rod off the rack. There are cheaper options available like the Shimano GT special which can be had if you shop around for probably $350-$400. I personally think you're better off with one of these than a custom built off a blank that isn't specifically made for GT popping.
On your final question, the Kamaja range from Valley Hill is an old range of jigging and popping rods from that company. Valley Hill is not a company we see or hear much of outside of Japan although the range of jig rods they released a few years ago (the Exploder range) have proven to be popular. I have a vague recollection of a the 7 foot jig rod although I have never seen it in the flesh. I don't think this will be suitable for casting poppers. Ideally, you want a rod that is at least 7'6"