Many straight bar Liverpools are reversible, with one side of the bar being smooth and the other side rough. I find this type of adjustment is frequently not due to any real safety need but rather the insecurity of the driver. Don't use more bit than you need. Many people asked questions about attire. A hat, gloves, apron or lap robe and whip in hand are absolute minimum additions to your wardrobe.
Hats can make or break the picture.
Remember, the hat should compliment your turnout and your outfit. A ladies hat with lots of feathers is beautiful but really a bit too much for a road cart. Likewise a top hat for a man. Your attire should be in keeping with the original use of the vehicle. That does not mean you need to wear period attire, indeed you would be incorrect in doing so, but rather dress for the typical use of the vehicle.