Do Suhr Modern guitars ever have decorative tops like Flamed or Quilted Maple tops?

Yes. Alongside all the Natural and Satin finishes, the Suhr Modern is often available with spectacular Flamed, Quilted and Burled tops.

Suhr Modern guitars have stainless steel frets. Why is this important? And what are frets normally made of?

Frets are normally made from Nickel or an alloy that contains Nickel. These are fine but eventually wear down and need stoned and finally replaced. Stainless steel frets are by a huge measure stronger than nickel frets. They will last for decades and decades without becoming dented or tarnished. Stainless steel frets are as good as it gets.

Some Suhr Modern guitars have 'roasted maple' necks. What does the roasting do?

Roasting the Maple in a kiln at very high temperatures takes all the moisture out of the neck. This makes the neck lighter, stronger and more stable, as well as looking beautiful too!