Why should a person join a guild? What are the benifits?

What are points for?

Are there ways to get items that are not in the armory?

Thanks

points are for upgrades for your account, like more turns (per hour), a bigger item backpack, etc.

you can buy items not found in the armory only from other players, at least currently

if you join a guild, the people in that guild cannot attack you anymore, most guilds hold contests for their members, and can help grow and get items

I am still not understanding why one would join a guild. They tax your winnings and take away from the people you can attack. A little lost. 

raids, protection both trough help during attacks and helping with personal vendettas, some guilds hold compet*tions with rewards and so on

what is a raid and how do they help in attacks?

From your point of view, it will probably reduce the number of people preying on you than reducing your prey

Joining a guild is very beneficial because they automatically join attack you make, and also help defend you in attacks against you.