When removing the tailshaft from the transmission will a lot of transmission fluid run out?

Nope. Just a few drips. You'll lose a quart or two when you pull out a half shaft from a front-wheel-drive transmission unless you have that side of the vehicle supported higher during the service. With rear-wheel-drive transmissions, only a little fluid finds its way to the tail housing to lube the bushing the drive shaft rides on, and the splines the shaft slides back and forth on the tail shaft.