Going back to the first question you asked.
To start your ATPL theory exams (6 months course) or to do the CPL or IR exams instead, you have to have to been issued with a PPL book. You cannot sit any ATPL exams without having a gained your PPL Licence. This is for the modular route.
If you do the CPL or IR gorund school exams and gain there ratings. Then you choose to gain an ATPL licence you will have to go back and do the ATPL theory exams.