A sarcastic bump will usually make me avoid, not come running to help. I don't have too much time to help people, and most people who answer tech questions have busy jobs too.
Anyway... playing an mp3 on the page is pretty much only done with a plugin. Usually either media player, quicktime or real player. Flash is the best choice though, as it's got an install base in the high 90 percentile (something like 98%) while the next best is around/under 75%.
Here is a lead for what I am recomending:
http://www.wimpyplayer.com/
The second question is very unrelated and really should be a separate thread, but the short answer is that Flash is a technology by Macromedia and their software (appropriately called "Macromedia Flash") is the standard authoring tool.
See here:
http://www.macromedia.com/software/flash/flashpro/
Note that Macromedia opened up the flash format for other companies to make authoring tools for and some are less powerfull and subsequently easier to master.
Here is a very popular one: Swish
http://www.swishzone.com/
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