All of that can be done much more efficiently without the mouse:

- scrolling with a mouse wheel

    :h scroll.txt

- selecting/resizing a split window

    :h window-resize
    :h window-move-cursor

- jumping to a specific place in the code

    /foo<CR> 

or the myriad of cool things in

    :h motion.txt

- making a selection

    v{motion}