Help design the output of a coaxial chimney

Hello, I'm from Belgorod. A question. Above the boiler room there is a mine (a wooden box sheathed outside with metal tiles) into which ventilation pipes are removed from the kitchen, bathroom and boiler room (each channel has its own channel). The coxial chimney from the boiler with a closed combustion chamber can be led into the wall, but it will come out under an open carport (this is temporary, then we plan a full garage). Those. the chimney after leaving the house will need to be turned either to the side or up to the roof.

Is it possible to bring a chimney into the mine? But then a few questions arise:

• Is a steam trap needed? Or is it possible to drill a hole in the knee between the horizontal and vertical sections of the chimney (this will be, the shaft is a little away from the place where the boiler will hang) and insert a hose to drain the water?
• Will the chimneys not freeze in the frost?
• And will the smoke from the chimney enter the ventilation? Will valves on ventilation pipes save from this?

Thank!