Hi,
1. with your BW background you can do the technical side of the BPC, you need to understand how BPC cube works and stores data, it is different to BW. If you know ABAP then that will be very beneficial. you need financial and excel skills to become a good functional consultant.
2. ask your company to sign up for e-learning, study BPC 420 is enough for your role.
3. BPC and HANA are different products, it all depends what you want to do, if you learn HANA modelling then you are not limited to BPC.
Andy