FTG is not exactly Minato's speed, it's a technique that results in Teleportation. That is a misconception. Madara moved out of Sasuke's range, which means by the time Sasuke realized that Madara had moved past it, he had covered even more distance for him to cover. For him to surprise the guy with foot speed that was above his previous tier proves how fast Sasuke was.
Madara was not distracted. Where is your proof? Madara saw Sasuke coming and outright commented that how fast Sasuke was. He didn't venture anything along the lines that, 'my god, I got distracted'. There is nothing in the manga to prove this.
FTG is instant, whether it's Tobirama's or Minato's. He was talking about Body Flicker. But I gotta say, Minato uses the term Shushin no Jutsu for his FTG as well. I have no idea what Tobirama meant at that time then.