PostgreSQL, integer arrays, index for equality

Question

I have a huge list of integer arrays (300,000,000 records) stored in Postgres 9.2 DB. I want to efficiently search these records for an exact match (equality only). I have heard of the intarray module and the corresponding gist-gin indexes. I would like to ask the following questions:

• Does PostgreSQL uses a hash function for checking equality of integer arrays or does it perform a brute-force algorithm comparing one-by-one the elements of the array?
• If PostgreSQL uses a hash function, is there some PostgreSQL function code to actually get the hash function result for a particular array?
• Which index will be best for such a task? B-tree, or the gist - gin indexes provided by the intarray module? The dataset will be static, i.e, once all records are inserted there will no more insertions. So, building index / updating index time is not important to me.