Iphone & mail setup

Hi all,

i have setup my email on the mac (and all works fine) and it is pushing emails via mail app to mobile me which then my iphone is linked to.

Questions are :

why wont my old emails on my mac transfer to the iphone? ie none of my inbox or outbox has transferred over but my drafts has.

if i delete an email off the iphone why doesn't it delete off the mac?

Should i be using mail app or maybe entourage?

thanks