As a rule of thumb, one should wait for at least one month to do laser treatment after finishing the oral Roaccutane treatment. Because the use of Roaccutane may increase the complications due to laser treatment, eg development of pyogenic granuloma on the wound.
And for your 2nd question, please understand it is very difficult to give you the advice without the knowledge of the type of pigments, depth of the pigments, and the type of laser treatment you are undergoing. You are advised to seek a proper consultation by a doctor with knowledge in laser treatment.