I can answer on #5, your written English is excellent. I am an American who has worked as an engineer in many countries, and am a bit curious as to why this is

I can answer on #5, your written English is excellent. I am an American who has worked as an engineer in many countries, and am a bit curious as to why this is true. When I worked in Japan, the education system there required years of reading and writing English and I never had any technical difficulties at all with the written English of my Japanese co-workers. I found this to be generally true in most of my engineering work around the world.