I suggest using a tenkara line that is about the length of your rod, before you add the tippet. This seems to be a great "standard" that you can use with most rods. Everything is different because some are stiffer than others. If you're on a big lake, get the longest line you can handle so you have better range.
I use just a couple of flies… mostly dry. I can't reveal my "winner" on the forum because its just so damn successful, but I will tell you that you should get in touch with Chris "kiwi" who ties flies and sells some on Tenkarabum. His flies are excellent quality and tend to yield me the most fish, so far…
In terms of fishing the kebari fly and what to choose for line, I suggest watching the videos on tenkara usa, and reading a lot of the tenkarabum blog. You will get all sorts of info from how to fish the flies to the types of lines. There are many different opinions, but its good to see it all yourself.
The one direct piece of info I can provide that SHOULD be useful to the community is this great site for buying hand made tapered lines/leaders. I personally don't like the ultra light weight of the level lines, especially the thin ones that tenkarabum uses. I only use them in the northeast on very small streams. These are limited to success in very tree-protected streams where you don't have as much wind, or on days when there is literally not even a breeze. They are not easy to cast with anything but the lightest of rods. More like for tanago fishing.
If you're trying to throw a dry fly on an "average" tenkara rod, with a lot of wind resistance on a breezy day, that fine floro level line just won't cut it. I also don't like using traditional thick "western" level lines. They don't cast as well and they seem to spook the fish more, not sure why.
I find that the best lines are furled tapered lines that give the rod a little bit of something to throw. ESPECIALLY when you use a bigger rod, or a smaller stiffer rod like the kiyotaki rods.
Check out this guy's site, I'm sure you'll be impressed. Custom everything, he makes some good lines and they can be made as small as 7 feet long:
http://streamsideleaders.com/