2. You are assigned a BGP Autonomous System Number (ASN) as part of the process. The IPs are assigned to your ASN.
3. You sign a peering contract with ISPs and peer with them using BGP on your router. You use your ASN to announce your block to have traffic routed to/from your router.
One of the tragedies of IPv6, IMO, is not having a better/streamlined process for end users to get allocations without all the red tape. There's tons of space, let's pretend it's the 90s and give away IP blocks to whoever asks. Either require ISPs to give static allocations or make it easier for getting a personal block. No, prefix delegation is not good enough.