Someone else just posted a question about mapping too, so I'll refer you to my answers on that thread to begin, Network Atlas - Map images, what map API and child maps question
Getting into some of your specific questions as well, there is no built in capability to change the graphics in bulk which is super tedious so the trick that I use is basically to steal a page out of Visio and create a template map. I load it up with all the icons I like to use, sized how I like them, and all the extra information I normally want to include in the captions with those types of objects, set up my preferred font and color settings etc. Don't assign them to any specific node, just leave them there and save it. Then when I'm building out new maps I just keep my "template" map open and copy the objects into the correct places on the new map, right click the object and go to properties and set it for whatever node i want it to represent. I wish I had a screenshot of one of these handy but I haven't done any Atlas stuff with the client I'm working with this month.
Also make sure to use the arrangement buttons on the edit page, i always see people struggling to get things lined up straight in Atlas and it has some buggy behaviors that make that feel impossible sometimes. The arrangement buttons make that a lot easier.
- Marc Netterfield, Thank you kindly - more stuiff for me to read from your good self 
Love that template idea and will definitely look to incorporate that.
