Ans 1. Amazon charges based on usage per hours.
Check the Amazon AWS Free tier details : https://aws.amazon.com/free/.
The free tier includes:
1.750 hours for Amazon EC2 Linux/UNIX or RHEL or SLES.
2.750 hours for an ELB plus 15 GB data processing.
3.750 hours for Amazon EC2 Microsoft Windows Server, Micro Instance usage (613 MB memory and 32-bit and 64-bit platform support).
4.30 GB for Amazon Elastic Block Storage, plus 2 million I/Os and 1 GB of snapshot storage
Ans 2.Elastic IP addresses
Allocation and usage of one Elastic IP addresses per instance is usually free, see the section below for Elastic IP Addresses on Amazon EC2 Pricing:
Region: US East (N. Virginia)
$0.005 per Elastic IP address not associated with a running instance per hour on a pro rata basis.
$0.00 for one Elastic IP address associated with a running instance.
$0.00 per Elastic IP address remap for the first 100 remaps per month.
$0.005 per additional Elastic IP address associated with a running instance per hour on a pro rata basis.
$0.10 per Elastic IP address remap for additional remaps over 100 per month.