Another question kinda......I can see why you shouldnt use my pipes to go thru the ceiling or the attic, but mine is outside, goes thru fireboard to get outside, the up about 15 foot. The fire board gets warm, but nowhere close to hot. At the top I have a T for a cap....i can put my hand about 2 inches from the ends, and its pretty warm air, but not hot at all. So....why would they make a telescoping piece, if its only to connect to a chimney? Just curious.
I dont know what fireboard is. Ive never heard of it sorry, but I imagine you are talking about potentially something that is like cement board?
Having a T at the top for a cap obviously (hopefully obvious) would never be something any inspector, code enforcement or insurance adjuster would consider ok. The first and most obvious risk would be for animals to get in there, blocking your flue gases from escaping.
I hope you have a carbon monoxide detector near you.
Your setup may work very well, for a very long time. Quite often, non standard setups for anything, people dont realize a point of failure until it happens then it seems so obvious to them. I think if you put 3 experts from these forums at your place to inspect, they likely would each miss one thing wrong with the setup (and it sounds like you have many).
I would seriously consider taking pictures and then follow on pictures when asked for, to understand your setup and what you should do vs what you are doing now.
No one here will advise you that it is wise to run the way you are. I think (and have learned) there are enough dangers already with a properly installed, drafted stove. Throw in more risks and well, your risk for a catastrophic event goes up exponentially I would imagine.
To answer your question about the telescopic pipe. It is used to connect the stove to the ceiling support much easier. That's all. In my setup, I have a 45 deg elbow going from the ceiling support box, then a telescopic pipe running at an angle then another elbow pointed down toward my stove. I adjusted the telescopic pipe so that the second lower elbow was directly in line with the flue collar on the stove. I then used a 24" piece of stove pipe from my stove (on top of a stove adapter which takes you from your stoves flue collar to teh type of pipe you are using) then I used another telescopic pipe from there to the bottom elbow so that it would all mate up nicely. Then I screwed everything together after ensuring it was level and plumb. If I have to remove all of this, I would 'simply' unscrew the pieces and slide the pipe together more closely to clean, move the stove, swap out the stove for another. Im set, I wont need to buy different pipe and can put it together rather easily, with some sweat and swearing.