The usages of "な" you said are all correct. ------------------------------ For "な as in 見ているな", it emphasizes the action, "見ている" "きさま" is a very rude expression of "you". (A long time ago such as 1000 years, it was an honorific expression, though) Therefore, the nuance of "きさま！見ているな！" is like "Hey you! What the hell are you looking at!" This is my example just for the nuance, thinking of "きさま" is used here. The direct translation is like what you said. ------------------------------ The nuances of な/ね for the above usage depend on situations: "The cute dog is looking at us. かわいい犬がこっちを見ているな/ね" "これいいな/ね This looks good. (doesn't it?)" Men may prefer な, e.g. when they talk only with men. ------------------------------ The negative imperative form is "見るな。 Don't look." In this case, It's always 見るな; NOT 見るね ------------------------------ I hope it helps.