Not currently when the Redguards are unified. It doesn't matter if the Bretons get attacked first. Orcs just won't make it passed the Redguards. Hell there is a reason why they celebrate defeating the Orcs. Not many other races could have done it.
Redguards are never truly unified. Anyone landing on your beaches while you're unprepared can run you out of town. And they just keep coming. They're not so great.
No, all they did was beat the original denizens of Hammerfell, the Orcs (twice), the Bretons, the Left-Handed Elves, and Tiber's little legion (Sorry, Stormcrown. No outright conquest for you).
Btw the orcs aren't very bright. Most are just taught the arts of combat and/or military discipline, very few dedicate to study, things like strategy and combat tactics aren't taught by just swinging a weapon.
Having many limitations in what type of fighting style they use is a big drawback to a strong race(physically but overall lacking)
Yeah, but Boromir was also a boss and in line to be steward of Gondor. He was a hero, not a common soldier. The cat that killed him, Lurtz, was a beast as well.