Well having just used my 2000 point kan wall list at a GT I can give some assessments on my personal experiences.
http://www.40konline.com/index.php?topic=209650.0I will say that i really wish I would have ran two big Mek's w/ KFF as it would have allowed me to split my wall and run it in two parts. This is crucial. As most of the game tables we were on had a large piece of impassable terrain in the center of the table it was really a kick in the tactics for me. Deciding when and how to divide my army worked for me but I really wish I would have had a 2nd mek.
The best thing that I found out works is having some upredictability. Snikrot with kommandos works great for me, I also use a squad of 10 lootas, and also a green baron. I used two green baron's this past time but honestly they didn't work as well as I had hoped.
as far as 9 killa kans go. I wouldn't recommend it without two big meks as they would be hard to cover with 1. I have a hard enough time using 6 kans and 2 dreads and keeping them in kff range with obsticles and terrain.
-Lootas work great. Work for great fire support. The problem can be you will be shooting thru your wall so therefore will be granting your opponent a cover save. They are a good support unit.
-Nob bikers could work to flank ahead. The problem will be they will be unsupported as the rest of your army will be moving very slow. They could work to tie up your opponent or alpha strike something. The big problem here is the points cost though. And if you want them scoring u need a boss on a bike. At 2000 points you will see a good sized nob biker squad with boss costing over a 1/3 the cost of your army. Again. in a speed freaks list you could do it. In a kan wall list you will see it will really limit the options you can take.
-Nobs and boss in a trukk will also fall into the same problem as the bikers.. they are going to be too fast for your army. Not to mention the trukk will probably be one of the first things to get popped. I tried fielding nobs on foot with a boss w/ BC. It was an ok unit. But really didn't add that much to my army or its function.
-grots. a good backfield unit, can work to screen your lootas or use as a backfield scoring unit. Can go to ground if they get fired on. or be lined up against a board to prevent outflanking. I would recommend 12-15 with a runtherd.
I will say the biggest contributer to the success of my kan wall is snikrot though. He causes my opponents to overreact and keep stuff back. Allowing me to get my kans / wall into position.