Mongodb Migration from Atlas to EC2

I actually have my mongodb databases in atlas and i want to migrate to EC2. I started with the QA testing using mongodump and mongorestore but this process took about 9 hours before I could have one available node. I am looking for a alternative faster method to migrate from Atlas to Ec2.
Also I am wondering if it is possible to add a 4th node from EC2 to an Atlas cluster having three nodes.