Instructions for development setup

I am new to go, I have cloned the repo and as per [archived] Building Syncthing, able to build syncthing. I need some basic instruction to setup development environment, Also some related questions

  1. I have seen go hello world, where it seems to run the code without building
  2. Some good tools to add a break point or debug it easily
  3. How to setup with sublime text 3 (read somewere project owner using sublime text)
  4. Things to do before sending a pull request like running tests etc ?
  5. How to make changes to gui, without rebuilding it ?