Tong-ah - Construction

Hello, I would like to construct tong-ah as the title suggests. Although I am aware of topics on ATARN, as well as one on this very forum (not how to, though). Still, I have some questions, and since I wouldn not want to loose my left thumb (any part of my left hand, for that matter) I am creating another topic. Also some of the topics are old and pics are long gone, or I simply want to get more info on some aspects.
I have a piece of bamboo about 3 meters long, which inside diameter goes from 12 mm to 20mm on the other end. What I am most interested in is:
-diameter of the tong-ah and it's lenght, would one meter be enough? I am shooting KAYA KTB 45# which I try to drawit behind the ear but it is not easy for me
-weight of an arrow, so that it does't demage the bow to shoot it (I am planning on 160 grain arrowhead and 10 mm thick bamboo)
-it's lenght (40 cm?, I read about 60 cm, which seems a bit long)
-at what point whould it start to close it, so that it does't fall out? I take it that it has to be opened as long as the bowstring is pushing the arrow
-i've seen arrows haveing thick "mass" attached near the end, presumably to keep it in, would epoxy resin work here?
-would it be a good idea to cover it with some kind of fabric  on the inside to reduce the friction between the bow string as well as make it eaisier on the fletching.

I would be grateful for any other piece of information, from someone with experience in shooting it.