About Google Adwords Match Options?

I has just opened an Google Adwords account for my business. However, I am struggling in the match options Google provided – exact match, phrase match, broad match. I clearly understand the meaning of all these terms, but I wonder why it is needed to bid on exact wording in exact match or phrase match if broad match can show perfectly and the bid price is the same (which Google suggests).
Also, if I have 3 exact wording of keywords in exact, phrase and broad match and with same bid price,
1. [memory stick] ** 0.05
2. “memory stick” ** 0.05
3. memory stick **0.05
if a user types in (sony memory stick) in Google search, then which ad, the second phrase match or third broad match will show up?
How about if the bid price is not the same, let’s say,
1. [memory stick] ** 0.5
2. “memory stick” ** 0.4
3. memory stick **0.3
If a user types in (memory stick), which ad will show up?
Thanks for helping~