Use Amazon EC2 for your infrastructure (including the OS, Networking, Storage, Compute, etc.). Create an AWS account for free here.
Use Ansible to configure your Operating Systems, deploy software, and manage the configurations on your servers in AWS. Puppet and Chef are other options too, but those require an agent run on your servers. Ansible just requires an SSH connection to your servers and you push out playbook runs across your servers whenever you need. It's idempotent so it only pushes changes that it determines are new to the remote systems.
I think Slack has a free version you can use if you want. That's what I've always used for Business chat.
Use Docker for you applications. You never have to manage dependencies on your servers when you deploy your applications using docker containers. You might have to manage things like versions of python and other OS centric software libraries, but nothing that would be a specific dependency for your applications. Everything is built into the container.