In a pure state, there is very little difference chemically between oxycodone and hydrocodone. Dosage guidelines are typically similar for each. Percocet will also have apap in it, the only oxycodone compound available that has no nsaid in it is oxycontin, if they still make it. Never take more than 1 gram of apap (even this is pushing it) in one sitting. Like most other nsaids, it is rather hard on the liver.
The gh releasing properties of diazepam are highly individual. One study I'm aware of comapared 5mg and 10mg orally with 10mg IV. 10mg both orally and iv increased serum gh concentrations in plasma to reach peak levels about 60 minutes after administration. Obviously, IV administration resulted in the highest level of stimulation. This "side-effect" usually subsides after several treatments, so I would not consider diazepam to be useful for any athletic purpose. In some patients, diazepam administation also increases serum cortisol and ATCH.
Both opiates and benzodiazapenes (with the possible exception of ambien, which really isn't a true benzo) offer little benefit to anyone intrested in strength training.