Your answer for:
Can I host a server by myself?
Not really but you don't need to
BAR offers servers for you, with the right configuration, latest updates, all kinds of nifty setup tools, robust networking and auto-downloads.
In the past we used another lobby, with which it is theoretically possible to host your own game. Unfortunately getting it installed has become increasingly difficult; making it work is even harder. Also there's a high chance hosting a server for BAR won't work over your internet/modem, since port-forwarding is almost always needed to make it connect to other players as well.
Owing to the many caveats of hosting yourself and many benefits of using the automatically spawned BAR servers; we recommend using the BAR provided servers.
We are working on making it easier to create your own server, only joinable by friends and managed by yourself, unfortunately we are not there yet.
Check out the #teiserver-spads channel on the discord if you have more in-depth questions.
The great news is our servers already have all the benefits of private servers!
Join an empty server with your friends and then type !lock in the battlechat. This will make your server fully private. Once locked nobody except admins can join or even spectate the battle making it fully private.