What does a conductor do to the overall dielectric constant? (see details)?

You cant change the dielectric constant of a material. the dielectric constant is used to work out the proportions of the conductor and insulator for certain line impedances etc. an example of this is 75ohm tv ariel cable ptfe and air are common dielectrics (air being 1 and ptfe being 2. the different constants mean different size insulators to get the same impedance