More than anything else, the Shop Steward (I used to was one!) is a primary point of contact for union-related issues in the shop, both for management and labour.
Is there s grievance with the management? Start with the shop steward. Does management have a complaint about a worker? Go to the shop steward. In many ways, teh shop steward is the civ version of a First Sergeant.
In terms of Union policy, the shop steward is also supposed to keep his eyes open for anything "hinky." His job is to make sure that union policy is not violated by management.
However, the shop steward is not normally responsible for reviewing plans and schedules and the like for any sort of compliance, but he IS supposed to handle anything that can become a problem.
In case you are wondering, the shop steward is typically the man in the shop with the most experience in place. The "second steward" would have as much as - if not more! - experience with the work and the union, but will not have been in the shop as long.
FFZ
EDIT - Jetlag, I have found that a good mustard will help your hat go down - I have had to eat mine on occasion. Make sure to have plenty to drink on hand as well - hats are both bland AND dry!
FFZ