1.) "Genki desu ka?" 元気ですか?: Means "you healthy?" but the context means "how are you?" (informal), "Nani ka(atta)" 何かあった??: a closer translation from "what's up" would be this, though. Very informal though :)
2.) "Hajimemashite" はじめまして: Means "good to see/meet you", or if you haven't spoken or seen to someone in a long time,"hisashiburi desu" 久しぶりです
3.) This one is hard to translate as there is no "literal" translation.. Instead, what's commonly used is "aitai" 会いたい: I want to see you.
4.) Not sure what you mean here, but if you mean it in a way like "whatever" as in "what ever", I believe "ikaga" 如何 would be the right term.
Of course my Japanese sucks, I did what I can to help, I was never really raised having to read characters that aren't Roman someone please correct me if I'm wrong with anything.