1. What is it even like, growing up in a language that has no gender-specific third-person pronoun? In English, we have he and she. If you are talking about an animate being in English, from the time you were old enough to speak, you had to think about whether that person was a male or a female. You couldn't continue the sentence without it. Yes, we have workarounds now with "they" or "he/she," but by the time we're old enough to use them, it's too late. We are programmed to notice, categorize, and then specify the gender of third persons.
In Finnish, they have hän. Hän can be he or she. Hän can be a man or a woman. When you talk about hän, you don't have to decide whether it's a boy or a girl. It's just hän. And it's been that way since you learned to speak (if you're a Finn, of course). What does that do to someone's worldview?
For one thing, it makes English a big old pain to learn, at least in that respect. One of the most common speaking errors (or hesitations, anyway) I hear from my students is she/he confusion. I had one student tell me something about his girlfriend. The girlfriend started the sentence as a he and only later turned into a she. When the student was done talking, I had to ask: is your girlfriend a man or a woman? We all had a good laugh about it, but dear goodness, how hard it must be to go from not categorizing this Thing to having to categorize it in every single utterance!
2. What is it even like, categorizing ä and a (and o and ö) differently in your head according to their placement on the keyboard? They each have their own key on the Finnish keyboard. Those of us who are native speakers of lame languages such as English that don't have fancy umlauts, who then study languages that DO have them, naturally characterize ä and ö and so on as subsets of their a and o counterparts. When I type, my fingers go for a and o, and only after a moment realize that ä and ö are completely separate letters. I am getting better at this as time goes by, but I keep thinking about those Finns and their brains and their keyboards and everything being wired a little bit differently when they learned to type.