What would be the benefit of making a group?

[Sir Spacey]

There isn't a static option to have it a private trading house or a real house; it's just what you make of it.
Some benefits are:
Finding more friends to play with
Gaining some leadership skills
The ability to host 2 house events per week
Gaining some trust skills
Learning/teaching how to play the game better
Sharing of gear (if you are on that level of trust)
Trade without suffering from a fee
Write a MoTD (message of the day) in the house page on the website for updates and ect.
Get your own personal Teamspeak channel

My advice to you is, become a follower before you become a leader. You benefit more that way, whether through knowledge or experience.