My mother tongue is Hebrew, I can't answer the second question because I don't get many chances to actually
speak English. Though I have been to London, and acted as translator a couple of times, and it did in fact became my thinking-language, however my environment still forces me to communincate in Hebrew (depressive!).
Though I've loved English ever since I can remember myself eating sand in the kindergarten, and always strove to understand it better... particularly through the computer and didactic books I've had, and when I finally got internet in 1995 I've gone berserk. I'll soon turn 20.
Thanks for asking.
Edit: I usually say - correct me in math and I'll never remember, correct my English and you are etched in my memory.

-Logwood