We're excited to hear that you're interesting in Linode! I'm a Linode user, but as I work for them I'm a bit biased. Lets see if we can get you some answers without bias, though.
1. Linode features availability for above
Linode will allow you to do everything you've listed, though, IAM is an Amazon proprietary service. As Amazon offers many different kinds of services that supplement their services, IAM helps businesses manage their users accordingly to all of them. Linode is a more simpler hosting provider, providing the most powerful server possible with fewer, but essential, extras - such as backups. To manage these services on Linode, you can create users and edit their permissions:https://www.linode.com/docs/platform/ac ... -passwords
You can add two factor authentication for extra security as well:https://www.linode.com/docs/security/linode-manager-security-controls
2. Linode Pricing/reliability compared to AWS
Linode is quite affordable, and in many cases much less taxing on the wallet compared to other hosting companies. I don't want to knock on any competitor so I'll leave this question for others, but Linode charges a flat rate for a block of resources as opposed to dynamically changing. You can see the prices here:https://www.linode.com/pricing
3. Migration issues if any that people faced
This one really depends on the process taken to bring the content over, but it's relatively seamless from every person I've spoken to. If you're pressed on your existing duties, our Professional Services team can take care of the migration for you:https://www.linode.com/professional-services
P.S. You can use the code 'linode10' for some extra starting credit.