Lit,
In your original post, your lines talk (or can talk) about so many concepts!
E.g. Free of charge; Subsequent free of charge; Pricing (B = Free of charge); Blocks - Billing, Delivery
When will the billing block be created and removed?
In Free of charge (or Subsequent free of charge) process, there is NO billing document.
Thus setting of a billing block is irrevelant or unnecessary!
My suggestion is to read the theory (of a process, functionality etc.) and then practice / check in IDES. These tool help in developing the skills for a functional consultant.
These tool help me.