Nope.
Whitebeard took off his medicatoin prior to Marineford, thus why he was unable to fight properly. That's it. It's quite clear you didn't know this.
That's irrelevant. Being strong isn't the same thing as being foolish.
Even Kaido had to lie and use trickery not to fight against Oden who almost defeated him. Dirty, but smart.
Sneaking into territory is no sign of weakness. It's simply intelligence.
Nope, not true.
You run when necessary regardless of ability to fight.
it's just intelligence and simply not wasting energy doing unnecessary things.
If you read the entirety of the Ace Novel, you'd know the rulers of the sea at the time were:
Roger running from Big Mom's territory proves nothing about his lack of strength. He just got what he needed and left. Doesn't change the fact Roger and Whitebeard were the strongest in their era despite the fact Big Mom and Kaido were around.
That's all it is, his physical durability and nigh immortality. Not being the strongest Pirate. It's the exact reason why he's referred to as strongest creature and not strongest Pirate.