• How does language allow self-reflection?
It allows you to make thoughts out of constructing sentences: You can create questions you might not have considered if you hadn't substituted certain words for phenomenon/words period. Like, you question something because you can form questions, but then through train-of-thought or purposefully you might change the noun or subject of the question to be directed at yourself. Like if you try to explain an outside phenomenon like "Why does it rain" and then "Why does rain exist" and then "What causes the rain" And then "Why am I thinking of this stuff, what the heck, I'm totally distracted I should be working. It opens up possibilities though. Without words there are just vague feelings and thoughts and language [as it grows] allows you to put this into words, and it sort of feeds each other [but sometimes they can't rep each other well maybe even subtract because even speaking is a transfer of information, so some data might be lost on the way].
• How does language organize perceptions?
This is a General Semantics question, and a good one. Every language has an implied world-view, and a way of categorizing/organizing everyday reality. In General Semantics, there is an oft-quoted statement, "The map is not the territory."
Focusing in on your question....Our thoughts are expressed via language...yet the opposite is also true, i.e., world-view which a given language implies also shapes our our thinking and perception. The two go hand-in-hand.
Allow me to cite an example. Languages will frequently have a certain "take" on sexual identity. In Spanish, e.g., one must make a choice of male or female. when choosing noun-endings. When speaking of a mixed group, one must use the male ending (e.g., "ninos," not "ninas")...which probably reflects a patriarchal world-view. In other cultures, e.g., in the Hopi Indian world, the emphasis is more matriarchal in character.
I'm going to have to review my anthropology, but I...