Some Fume Hood Questions

Hi, I am currently currently designing a fumehood for my home laboratory. The fume hood is intended to be an all purpose fume hood for organic, as well as inorganic chemistry. As the main building material I intend to use MDF covered Plywood, with fire resistant mineral sheets covering the inside. The aforementioned mineral sheet goods are about 1" in thickness and resistant to high temperatures as well as organic solvents and most acids.

However, I have come up with a few questions now:

1.: Considering that the exhaust pipe of the fume hood has a lenght of 3,5m at a diameter of 31,5cm and a total of 3 sharp 90° turns, how much m3/h do i need?

My calculation is that i need a face velocity of approximately 0,6m/s. Considering the fact that the maximum height of the sash opening is 0,5m at a width of about 2m. According to these measurements, I need an effective air flow of 2160m³/h, at the hood itself. But how do i calculate the actual air flow requirements for the fan itself?

The shape of the ductwork is as follows:

The radial fan itself sits on the southside of the building. With the pipe (d=315mm) exiting from the bottom of the fans case. From there it goes down 0,5m, followed by a 90° turn northward, followed by 1m of straight pipe, again followed by a westward 90° turn. The last 90° turn is a downward one located inside of the top portion of the hood at the end of the final 2m of the ductwork pipe.

Can anyone show me how to calculate this?

2.: How far away from the back should I place the baffles and the opening for the pipe inside the hood? How should I design and place the openings between the baffles? My idea was to use a simple 19mm thick board and cut the openings using a handheld router.