R1 Pro with Hotwire

Received my hotwire today and have started playing around with it but have a few questions .

When setting the lvc in custom for say myself on 5s i wanted to set it at 3.1v per cell so 15.5v .
Using the up and down arrows to adjust the figure i can't get it to exactly 15.5v it's just over at 15.546 or something and if i go the next one down it's just under at 14.986 or something.

Why can't you just use the numbers on your keyboard to set the exact figure

Also has anyone played with the push control feature , does it realy help in coasting with a brushless motor .This feature could be great for when you let of the throttle in the air and the motor brakes causing a nose dive ?