Do it yourself (Istanbul)

Hello fellow expats and locals. I know most of you are independent like me. If something breaks down, you try to fix it yourself. Every apartment building has a manager, but I am not sure if he is there to help you fix things or not so I am reluctant to ask. Here are some things that I need to know more about.

Number one, I need to know if there is a way to fix the water pressure in my shower. If I turn it on, it runs cold. To get hot water, it must be a trickle. The water heater is so small.

Secondly, why do most buildings have a shaft? What purpose does it serve?

Thirdly, even the light bulbs are so hard to change because the ceiling is so high.

Lastly, how can you tell if your stove gas is about to run out? Obviously, if there is no gas it has run out but I want to know is there a gauge on the tank that shows how much is left? My gas just ran out after seven months.

I really hate calling someone over to my house to fix things that I could've done myself. All I need are some suggestions. Thanks