What are the steps to becoming a rules advisor and what kind of rulings can be made by one?
The Rules Advisor program has recently been discontinued. Becoming a level 1 judge is the entry level for officially judging.

The changes in a nutshell:


  
  The Rules Advisor exam is available until the end of April. Passing the exam no longer grants or renews the Rules Advisor membership, and all existing memberships will expire normally. Once the exam is retired, all content in that exam pool will be either reassigned to another exam or retired from use.
  The online L1 Practice exam is now available to all users. People interested in becoming a judge now have direct access to this resource, and this exam shows up on your Judge Center profile when you pass it. (Keep in mind that passing the L1 Practice exam does not grant any special benefit or membership.) If a particular store truly wants to require something to judge FNM, passing the L1 Practice exam is a far more reasonable requirement and more supportive of organized play in the long term since it helps lead towards Level 1 certification.
  The online L1 Practice exam now has a 28-day cooldown period. This should make for a training resource that is more readily available to all users, balancing the limited content in the pool with the need to make sure people can study and practice towards earning the Level 1 certification. Level 2 and Level 3 judges can still create the online L1 Practice exam for others, and still have the ability to generate written L1 Practice exams to administer in person. Use the resource as necessary to help people to pass and join the judge community.
  


Source: http://blogs.magicjudges.org/blog/2016/04/15/the-rules-advisor-exam-is-being-discontinued/