SQL Server transactional replication process and error [closed]

I need to setup a replication.

1. Which replication is better if I want to keep my data updated in the second server as soon as new data is pushed into the primary server.

2. I tried setting up by clicking on New Publication and got error message:-

So I found I need to use sp_addserver. How does it work, In which table it will add the server name. How will it affect my current setup if I change the server name. Will my APIs or other services connected to this server will start failing if I chnage the server name.

3. A step by step guide for whole replication setup with details would be helpful.