if you can't type the accents because of the keyboard you use, it's acceptable to replace any accents with the letter x following the accented letter. so ankaux is the same thing as just the accent (even with keyboard add ons I can't seem to have the inverted arrow on top, only the upright cap)
Yes, I should have recognized it. I found an Esperanto Keyboard for Mulitling keyboard for android which I find easy to switch to from the Samsung keyboard. Now, for the Windows computer, I enjoy using Holdkey which allows me to type Win 5 then u for ŭ: http://www.holdkey.eu/ https://www.duolingo.com/comment/8841170
"Rapide" is an adverb, so it's "quickly". "Quick" is an adjective. In many contexts (especially when speaking rather than writing) you could say that someone "learned quick" without anyone raising an eyebrow, but in a formal linguistic context like this it's considered incorrect.