In BJT CE configuration, is it correct to write Ie = Ic+ Ib? Shouldn't it be Ie= Ic-Icbo + Ib?
"The collector current Ic comprises of two components. 1)alpha times
  the Ie, 2)the reverse saturation current Icbo...."


$$I_C = \alpha I_E + I_{CBO} \tag{a}$$ 

Now,
$$I_E = I_C +I_B\tag{b}$$

then,
$$I_E=\alpha I_E + I_{CBO} + I_B\tag{c}$$

I think you used the approximation that \$I_C = \alpha I_E\$ somewhere in your calculation. Remember that \$I_C = \alpha I_E\$ is valid only if \$I_{CBO} = 0\$.