Hi Andrew,
All your questions are possible in BPC, standard BPC doesn't come with any planning calculations, best bet will be using ABAP custom logic like Vadim suggested.
Personally I don't believe in BPC RDS, RDS is a way to get customer interested, but you still need to do the bulk of customization in the RDS, unless your business fits what RDS provides, else it is better to start from fresh installation.
Andy