Stuck in Ri, Rout and Av calculation for BJT circuit!
The gain of the emitter follower is a bit less than one. To find a relation for Av you just need to find vo in terms of vi. Based on your small signal model, we have using kcl at node vo:

$$\frac{v_o}{R_E||R_L||r_0} - g_m V_\pi - \frac{V_\pi}{r_\pi} = 0$$

Now you need to find Vpi in terms of vi:

$$V_\pi=v_i-v_o$$
Now substituting this back into the first equation you simply find for Av:
$$A_v=\frac{v_o}{v_i}=\frac{R_E||R_L||r_0}{R_E||R_L||r_0+\frac{1}{g_m}}$$

Just follow the same procedure to find input/output impedances. For example, to calculate the input impedance put a test voltage source Vt at the input and find Ri=Vt/It. For now just neglect RB we will get back to it later. 

$$V_t=V_\pi+v_o$$
$$I_t=\frac{V_\pi}{r_\pi}$$
$$v_o=R_E||R_L||r_o\times V_\pi(\frac{1}{r_\pi}+g_m)$$ 
Now Vt/It becomes
$$R_i=[r_\pi+R_E||R_L||r_o(1+\beta)]$$ 

This is just the impedance looking into the base. To find the overall input impedance including RB, you need to consider Ri in parallel with RB. Therefore the input impedance becomes:

$$R_{in}=R_i||R_B$$
The ouput impedance can also be solved in the same manner. Just put a test voltage source Vt at the output and solve for Vt/It.