Wireless Email

[#1]

I use Gmail on my computer, and as one would expect, I need to sign in to access my mail. I set up my phone to access my Gmail account, but it concerns me that I don't need to sign in. Anyone can pick up my phone and check my email now. Is there a way to set this up so that I can require a password to check email from my phone?

[#2]

Not email specifically, but you can set a PIN that can be X number of digits that can activate after a specified number of idle minutes

[#3]

Is the PIN for the phone, or the email application?

[#4]

it's to unlock the phone.