(a) In all actions and proceedings in court arising under this act all such process shall be served and the practice and rules of evidence shall be the same as in actions in equity, except as otherwise herein provided. Every sheriff or other officer empowered to execute civil process shall execute any process issued under the provisions of this act, and shall receive such compensation therefor as may be prescribed by law for similar services;

    (b) No person shall be excused from testifying or from producing books and papers in any proceedings based upon or growing out of any violation of the provisions of this act on the ground or for the reason that the testimony or evidence, documentary or otherwise, required of him may tend to incriminate him or subject him to penalty or forfeiture, but no person having so testified shall be prosecuted or subjected to any penalty or forfeiture for or on account of any transaction, matter or thing concerning which he may have testified or produced any documentary evidence: Provided, That no person so testifying shall be exempted from prosecution or punishment for perjury in so testifying: Provided further, The immunity hereby conferred shall extend only to a natural person who, in obedience to a subpoena, gives testimony under oath, or produces evidence documentary or otherwise under oath;

    (c) Upon application of any person the commission shall furnish certified copies, under seal of the commission and signed by the commission or its secretary, of any order made by it, which shall be prima facie evidence in any court or proceedings of the facts stated therein.