a). Yes you can easily do part-time Law. Some universities offer part-time LLB Courses. Some other private universities have relaxed attendance requirements, though the same is violative of the Bar Council Rules. You can enroll with any such university.
b) For someone with a degree in Software Engineering, Intellectual Property Rights, in particular Patents and Copyrights may be a good specialisation to look forward to. Also, since you have done diploma in Cyber Law, a career in this field may also be a good option. However the field is relatively new and I am not sure of the income earning potential of the same.
Finally, it is worth it if you are confident about yourself. But my advice- Do not do law, only to take forward your father's case against his company. Do law, only if you genuinely think you have the potential.