how long is a day in Hebrew?

Can the seven days of creation be interpreted four different ways based on the Tanach definition of the Hebrew word YOM? The Tanach has 4 different meanings depending on the context.

1) Yom as in daylight (12 hours)
2)Yom as a single day (24 hours)
3)Yom as a year or two
4)Yom can be an indefinite amount of time, such as the word 'b'yom meaning 'when, or the phrase 'Ad hayom hazeh' (until this day).

Unlike the modern Hebrew and English, biblical Hebrew had no other word for infinity, era or epoch.

Also note: Rashi, on Gen 24:55 translates the word יָמִים as year & Ramban translated the word YOM as era #jussayin

Here's ahh cool blog supporting the idea:
http://dovbear.blogspot.com/2007/11/yom-does-not-mean-day.html