I'm thinking about getting Arduino UNO + Ethernet shield with POE and try to build like a token ring with some hubs. (Let me know if i'm wrong please)
Why does a "token ring with some hubs" seem like a good idea? Next time you are in a classroom, look around at all the computers. Do you see a "token ring with some hubs" anywhere?
I find Ethernet a good idea because the pipes are buried so a wireless connection wouldn't work.
Are you planning to dig the pipes up, to bury the Arduinos with Ethernet shields?
I would like to ask you if you could give me some advice in which is the best way to go and how can i make it work, at least my 2-3 arduinos prototype.
If I recall correctly, this is YOUR degree program's proof that you learned something. Having us do any of the work for you simply proves that you didn't.
If you have SPECIFIC questions, it is perfectly OK to ask for help/clarification/etc. It is NOT OK to ask us to do the project for you.