I have a 3799 and I am very happy with it. It is the exact same watch as in the movie "The Bourne Legacy". This model existed and was in the IWC catalog until 2012. It is in 2013 that the entire line up of pilot chrono watches (except the 3777) saw their sub dial layout changing from seconds at 9 o'clock position to 6 o'clock position.
The movement used in thees pilot's watches is a derivative from the famous Valjoux 7750 now manufactured by ETA under the same ref number. IWC has added an extra plate and a module of three jewelled gears that are transferring the seconds from 9 to 6. Unfortunately our dear Asian friend have done the same but without jewelling the gears. This creates extra friction and drag on the movement therefore it gets the movement not to last very long.
To answer your other question about the pusher at 10, yes, it is functional, well it does not activate anything, but it is a real pusher with a spring just like the 2 others.
Although it is 46mm, I wears quite small. It fells just like my 44mm PAM, and maybe a bit smaller.