the x axes are accordingly labelled as either temperature in K or velocity in m/s and the y axis for both are the radial length from the centre (these are temperature and velocity profiles for the cross sections)

and no the pipe has three named sections (velocity inlet, velocity outlet, and wall) and the HTC is including the entrance length. 


from the graphs and calculations, the flow is fully developed after about 20 diameters so I will create a separate section there to measure the HTC from. However, the nusselt curve or HTC curve measures the nusselt number or HTC at each individual  axial length coordinate rather than the whole section.