Do you need to consider scoliosis and subluxations in the back when getting treated for herniated disk?

Potentially. If the condition is mild, then simple and conservative treatments don't necessarily require a lot of specifics; such as for example rest or medications. Once you get beyond that, however, it becomes more important to identify all the specific conditions that are contributing to a patients problem.
Only if thinking OR. Not for non operative treatment do you need to consider any scoliosis or deformity. However, these may affect outcome of non operative treatment and are definitely considered in operative planning where indicated.
Yes. Those conditions happened in the same area and your spine surgeon will take x-ray and MRI to see to see if you have this condition? And advise accordingly.