With disc or hub brakes the braking forces are the reverse of pedaling forces, so it makes sense to have the spokes reverse from drive side too. Any braking or pedaling torque transmitted through the hub would move the rim to side if the , so it makes sense to build the front wheel wheel which isn't driven with mirror symmetry.
Now, why this orientation? ...
Yes it fits easily, I use a 26x2.125 tire on a 26x80mm wheel. Gives a nice low profile look. Just use the non puncture proof tubes, so it can shape itself to the inside of the tire. I'm going to use 26x3.0 tires on my 26x4.0/100mm wheels
Most likely you need:
26 tpi (thread per inch)
On the website below there is a list off all Shimano gear hubs which use this size nut:
Please check if your hub is listed to ensure compatibility.