As an update, and if anyone would like to know in future, I’ve deployed a SHOUTcast server in realms of Digital Ocean which auto restarts SHOUTcast if/when the server reboots.
The following info represents days of searching, testing, and tweaking to get everything just right. And as a good citizen of the mairlist community, I wanted to share the love.
Digital Ocean - Info & Server Selection
I regards to the max listener count, a physical Digital Ocean server that contains the Droplets (there version of an AWS Instance, aka a virtual server) use a shared 1Gbit/s port to the data centres network. So assuming that multiple Droplets will exist on any one server, I opted for a max listener count of 781. This listener count is based on a 128Kbps stream, and assumes at most I will have a 100Mbps connection. I then reduced that to 750 max listeners, this gives me some headroom. I used the Orbital Grooves Bandwidth Calculator to do the math, because I’m lazy 
As for the server, or Droplet, I opted for a $10 / month plan. That gives me 1GB Memory, 1 Core Processor, 30GB SSD Disk, 2TB Transfer. Not sure how data transfer will go, as I’ve not completed a month of broadcasting yet. Although I’ll update this thread when I have a better idea. If you’re planning to use Digital Ocean, please be a good sport and use this link: https://www.digitalocean.com/?refcode=69b15098bc9b which will give you a free $10 credit in your Digital Ocean account, and I’ll get a little love from Digital Ocean in return.
I’m using CentOS 64bit OS and a 64bit distro of SHOUTcast 2.4.2 (currently), plus additional security and what not on the server itself. I suspect as the station grows I’ll need to deploy extra servers to spread out the traffic, which I’ll do when I reach that stage.
SHOUTcast - Installation Guides & Tips
I used this guide vpsshell.co.uk/index.php/centosrhel-installing-shoutcast-server/ to do my installation, but be aware that the install files are not same since version 2. You need to head to shoutcast.com/broadcast-tools to get the download links emailed to you. Rest of the guide is good though, although I installed only the DNAS server and not the transcoder, as I’m only doing live streaming.
To solve the problem of auto starting shoutcast on server reboot, I used this guide nathanskelton.com/blog/?p=576 and it worked perfectly on my CentOS 6.x 64bit installation.
Configuration is up to your own personal requirements. However in my configuration I used full paths when defining the logfile, w3clog, banfile, and ripfile. This means that in theory any user (with correct permissions of course) on the Linux OS can start the shoutcast server, which is useful when using the auto start script I mentioned above.
Hope this helps someone else, as it did me.