Experienced over size driver getting into regular step deck hauling need all advice and tips please!

I drive flatbed 5 years and never stop learning. Just tight down your load, learn to work with straps (you're enough experienced with chains), never stop paying attention to other guys how they do secure their loads and never feel ashamed to ask.
Your only hard time will be how to tarp uneven high loads, oh boy, had hard times when used to drive step deck for couple of months!

 

You'll get it. But like corfu said dont ever be ashamed to ask the drivers if u have any question, us step deck flat bed guys always try to help one another especially when just starting out.

 

Is this a 53? Fixed or movable axles?

One of the primary things to know is your load center for each of the axle settings if movable.

Some states besides Cali have kingpin to axle center regulations. FL, VT are a few that come to mind.