Through-wall chimney- question on horizontal pipe

Hey guys, I have a coal stove base burner that Ill be installing in my basement. Since I am going through the wall in the basement, I will need to have both a vertical secion of pipe off the stove and it will need to transition to a horizontal section via an elbow to the wall thimble.

my questions:

Does the horizontal section of pipe need to have a upward angle (like 1/8" per foot, or can it be perfectly level? It will be short section of horizontal pipe (approx. 1.5 ft)
Also, how does the stove pipe attach to the stove. I have a cast elbow that has no drilled holes in it to connect the pipe. Does furnace cement need to be used for that or should i just drill and use screw to secure the pipe?

Are there any critical dimensions for chimney and stove pipe installs that I need to know about? (Ie- does the vertical stove pipe coming off the stove need to be a certain length, etc..)
Thanks for the help guys.

-Steve

Short horizontal pipe can be level or with slight rise.

You might run into trouble connecting to that cast elbow. The pipe might be too tight to go over the casting and too big to go inside. Back in the day smoke pipe was riveted instead of having a folded over seam as modern pipe does. As a result modern pipe is slightly smaller. Using a curved face hammer that seam can be flattened and the pipe can be stretched a bit at the end to fit. Use at least one screw. That may or may not lead to a problem attaching to your SS chimney as the crimped end is now toward the chimney. When you get your chimney you will see how it goes.