I'll take a stab at this (no pun intended).
The sweep in the leading edge of the stab as far as I know is mostly a function of asthetics. Wing sweep in full scale aircraft is generally employed to delay the onset of critical mach number (this is when airflow goes supersonic over the top of an airfoil and sets up a shock wave). It works because the speed of the approaching air becomes a trigonometric function of the sweep angle. Obviously, in models this isn't a factor especially on the stabilizer.
The size of a control surface is really determined by the speed the model flies at and how much force you want the surface to exhert. First, let's start with a small surface that is very wide. Let's say your flying slow but you want to do some abrupt manuever. The force the control surface produces is a function of the surface's area and angle of deflection. If you don't have much area then you'll need a lot of deflection. The problem is, if you deflect the surface too much then the flow over it will seperate. The solution is to give the surface more area. Consider the profile planes you mentioned. These aircraft are designed to be highly aerobatic at slow speeds, hence the large control surfaces.