Balancing the Data ,Replication ?

Hi,

I have two sets of data i.e two instances of SQL server in two different cities. Data entry happens at both the places.I need to balance the data in two servers i.e. I need to Synchronize the data.

Currently I am Exchanging the data between two sides and using a Buffer database to update the incremental infromation.(Running a SQL script).

I have GUID columns in my database. I am too new to replication.I wanted to know whether I can implement repliaction and what changes i need to make?(e.g. Replacing GUID columns with Identity columns).
Permanent connectivity between two databases is required or Replication can be performed whenever connected?

Best Regards
RohitCan two databases having GUID columns can be replicated or needs to be altered to Integer column