no the scroll wheel only clicks down(like a button). but using the Logitech gaming software you can bind scroll left and scroll right to any of the keys.
YES!! This mouse was built for that. I use it for all my games. Just download Logitech Gaming Software. I can't tell any difference with lag between this and a wired mouse.
I have not found a game where this mouse won't work with. I haven't play Fortmite yet but have played the Fallout and Witcher series with not a problem.
It also depends on if you are playing through something like origins or steam but yes, it should work without issues. mine worked with plug and play but for fortnite or any real gaming you will want to download the ssftware to assign buttons and more control/setting of the mouse. It can be used on win or Mac OS
I would use R to reload and L-Shift to sprint, but whatever floats your boat. I would say that the bottom 3 buttons are probably best for building, while the top 3 could be your main weapon slots.
I would never recommend a wireless mouse for gaming. Especially for a FPS. In a wireless mouse you tend to get input lag, disconnections, interface issues, and just general unreliability. Any wired mouse will be much better.