HRH I'm not Txonä Rolyu, I was saying "Like Txona Rolyu (Who is another member here who speaks great Na'vi)..."

Anyway, There are so many "that"s because that is the best (horrible) translation we can come up with in English. It's much more practical to learn what their meaning is by knowing what they are made of and how they are used. Most "That"s actually mean "this". ;D weird huh. We get around "have" by saying "Is to me a Thing" like this: Lu oeru ikran. (Is to me an ikran. I have an ikran) and so on. use lu and the dative form followed by whatever noun. The special characters come from a keyboard layout. If you are on windows, I recommend Kxwerty, a layout I made specifically for Na'vi.
My kxwerty KBL if you are on mac, just google "how to type grave i on mac" "how to type umlaut a on mac" I think it has to do with option and some other key and then a or i. I myself (a Linux user) use a layout called Dvorak alternate international.