The standard current dosages are 2.5, 5, 7.5 and 10mg.
This cannot be sensibly answered. A milliliter (mL or ml) is a measure of volume, grams (g), kilograms (kg) and milligrams (mg) are measures of weight or mass.
Roxicodone 15m is stronger, but to go from 100- 10m down to 35- 15m is only half the amount of Oxycodone. So you went from getting a total of 1000mg of Oxycodone down to 525mg of Oxycodone, he just cut your dose in half. Tell him to give you 60 Roxi at minimum.