Need help to jump start for creating proto type for porting existing flash app

I am looking to port stage3D based flash application which we created for architectural visualization. You can check a sample here (works only on flash supported browsers). It could be turn into as completely new product as a different solution, don’t know how it goes. Right now I am just looking to port as it is (more or less) as a prototype to show to my boss and discuss the future plan.

My learning in past 7 days

I have been watching tutorials and got familiarize with the editor, level creation and blueprints and also tried to study some of the sample projects

What help I am looking for (I might be not speaking in UE terminology)

I want to implement camera handling the same way it is in my current stage3D application.

How is implemented currently

Rotation: Using left mouse button to left and right will rotate the model. Moving mouse down and up will rotate camera on X axis around an anchor point (center or the world (0,0,0))
Panning: Using right mouse button to left, right, up and down
Zoom: Mouse wheel

What is the problem to get started

In my world (stage3d) I need to check for the mouse and keyboard events and move the camera accordingly. In this world (UE) I have lost. I have looked at the samples (Tower defense, 3rd person shooting and many others) and and I have not found anywhere to see where the logic is implemented to handle Mouse and Keyboard. What I have realized is that the controls are configured in the world settings by selecting the Game Mode where there are predefined classes which are implemented somewhere deep inside core classes and they inherited into the Pawn classes or Controller classes.

What I have understood is I need to create a new Game Mode blueprint and assign it in the worldsettings’ game mode and implement the logic in this blueprint which will handle your mouseevents. If so, please help me where to start. I understand that I need to create nodes of MouseEvent and do some action here but I am bit lost. Please help.

Thanks

In the editor, go Edit>Project Settings>Engine>Input.