Scott sub have been made in 26" and 700c versions.
A 700c x 32mm tyre is ideal for rough roads. What is your spec on the sidewall text?
Schwalbe Marathon are std quality commuter tyres.
Schwalbe Marathon PLUS have extra protection and ride a lot harsher.
the flat bar can be uncomfortable. I prefer a more swept back style.
You can fit aerobars to a flat bar or use trekking bars.