Dissimilar Metals - Weathering Steel

[pcronin]

I am trying to find out information about corrosion rates and concerns with dissimilar metals. The project in question is a set of bleachers with the original structure consisting of A588 Weathering Steel. Over the years, there have been many modifications to the bleachers including aluminum seats, galvanized posts and handrails. All of the metals at various connections are in contact with each other. My specific question(s) is as follows:

What are the concerns with the following conditions?
Weathering Steel in contact with Aluminum
Weathering Steel in contact with Galvanized Steel
Galvanized Steel in contact with Aluminum
Plain uncoated steel in contact with any of the above