SHADEWRECKS There is really nothing special about hangars so I dunno what you want to know.
Hangar parts are just corridors with special graphics. How you want them to look is purely your choice of selecting and placing them.
For docking other ships / drones / etc. just use the internal version of https://wiki.cosmoteer.net/index.php/Abh_mod/Docking_Reload_Station
It's the small one in the video above. It's been more than a year since they got added so the graphics and button are more advanced / convenient to use. All you need is make sure they got supplies to transfer. Then turn it on and choose the type of supplies. It's all off since you would be wasting valuable supplies if it's always on.
Docking ships should have collision avoidance turned off. Otherwise they will try to escape.
Get the ship close enough for the docking is all you need do. The docking part when turned on will activate a docking beam to draw in the ship. It's not strong and range is small, tough.
And for covering the roof just use the right sized / right handed https://wiki.cosmoteer.net/index.php/Abh_mod/Hangar_Control_Roof
You have to place it on the side or corner. This is purely due to the game's building mechanic.
Like with most parts their size / property is within their name.
Use blueprint mode to see directional arrows showing where to expect the coverage. Naturally, you have to use external view to see the roof. You can switch it to open / close the roof. In case you don't see it it might be closed.
That's all there is. This is a game so just play around and try out the menus and buttons. Read the descriptions / wiki. Only the most crucial have tutorials (power supply network parts) within the game.
And yeah, crew cannot walk into the hangar. If you must have it then use the catwalk parts.