Stick with HTC emails, it sounds like you're looking at the widget, rather than actually in the programme, if you go into the programme then check the settings, there should be options for the inbox to customise how many messages it loads...IIRC mine is set to 14 days?
Music player, if you only need mp3, and have 2.1 or higher is probably Cubed. Worth downloading mp3tagger to fix any dodgy ID3s with this too.
Cubed takes a bit of getting used to, but I much prefer it to the stock HTC desire player and also double twist.
You'll likely find cubed much easier to use once you change it to coverflow rather than cube view mode too.