2 issues - how to correct?

1. Voice mail - I have a voicemail sitting in my voicemail box, but because I did not have a password set up, it is saying I have no new voicemails, and not finding an option to get to 'old' voicemails. Anyone know how to fix this?

2. Emails - Nexus keeps redownloading old emails I have deleted off my phone, but not the actual acocount as 'new'. Should I open theemails then just leave them there? does this effect memory of my phone? Or is it like a BB and will eventually move off old emails as time passes?