"瀏覽" is a noun in Chinese as well as a verb, right? I found Safari used the wording, "清除瀏覽記錄" where "清除" should be a verb and "瀏覽記錄" is the object.

Somehow, I am not familiar with phrases like "頁眉" and "頁腳", so I recommend alternative.

As for "標題" and "註腳", I would suggest those to be "title" and "footnote" instead.

That's all right.
I don't use Chinese version of Firefox, Safari or even Camino. In general, I don't work with menus or dialogues in Chinese, so when someone gives me Windows or Mac that is in Chinese interface it usually slows me down a lot.

I only provide suggestions based on how the sentence sound, not from a user who use them.

Apart, personally I don't like direct translation... so I don't see the need to distinguish "無法" and "失敗". An overall flow of the sentence seems more important to me.

Well, I believe when you just use 瀏覽記錄 by itself, "瀏覽" is verb. When you write "清除瀏覽記錄", "瀏覽記錄" becomes a phrase.