I think all of that is for adjusting the scale and position of "Body", yes.
*GlStateManager.translate(0.0F, -3.6F * f5, 0.0F);
I think the -3.6 is the part which controls distance from ground. You can try changing that part.
For my mob. The if (this.isChild) is for a child of a breedable mob, and the "else" is for a full grown.