An Internet Gateway (IGW) enables communication between a VPC and the internet. It allows resources in the VPC to send and receive internet traffic.
Transit Gateway Peering Connections are needed to enable communication between VPCs attached to Transit Gateways in different AWS Regions.
Yes. VPC peering can be established between VPCs in different AWS accounts, as long as both VPC owners accept the peering connection.
VPC Peering is billed based on data transfer. There is no hourly charge for the peering connection itself; you pay only for the traffic that flows across it.
There is no charge for creating a VPC peering connection, but data transfer charges apply for traffic sent across the peering connection.