BlueÆther

I wouldn’t worry about ‘website traffic’ if you are using federated services: there is a shit ton of chatter back and forth between servers.

You could put the UI behind a simple password page but you will have to leave all the API urls open.

It takes time and effort to keep ALL the services update (as well as the host OS). So much so that I have actually taken down my wordpress blog

You can use a single domain and subdomains for each service. Once you start to host multi-services you will need more and more compute power and storage.