Stalker,
Xenomorph,
17 years ago
Predators see in a different light spectrum than humans do, which should be quite obvious. Much like a rattlesnake, they are able to pick out heat signatures from cold environments, although there have been some continuity errors as far as what they can see without their mask. In the original Predator, the creature's natural sight was a bright red, hazed thermal vision, although in Predator 2, its vision remained unchanged even after its mask had been removed, this was more than likely simply a continuity error.
As far as speaking fluent English, it has been seen that Predators are able to learn & understand different languages, such as the Elder from Predator 2, which briefly spoke to Harrigan without any audio cues.