Stop email copy/download to iPAD

If you're using the Mail app, you can't have it both ways. Either the mail is downloaded for you to see or it isn't downloaded and you can't see it. If you don't want the downloading, delete the account.

I don't know if the iPad Safari browser can be used to access gmail. I can't use it for MobileMe but I do use it for Verizon mail and there's no downloading. Try that and see if it solves your problem.

By the way, you might also configure the iPad for an automatic wipe after ten consecutive unsuccessful login attempts.

There's a lot of good information in the User Guide here:
http://support.apple.com/manuals/#ipad

Also, the (free) User Guide from iBooks is even more extensive and a worthwhile download.

Yes, you CAN use the mobile OR the desktop version of GMail web mail to manage Google mail from the iPad.

By as pointed out, if you set a passcode or pin (preferably the former), your iPad is AUTOMATICALLY encrypted. Whilst locked there is no way to access the encrypted data.

So choose a reasonable passcode and you will be very safe unless you are someone either high-profile or wanted by a government agency! In that case, I am guessing that there would be sufficient incentive for someone to brute-force entry.

Also note that the default settings mean that after 6 incorrect passwords, you are forced to wait longer between attempts and after the 10th attempt, the iPad is automatically wiped clean of data. For the really paranoid, these settings can be configured using the enterprise configuration tool for iPhones/iPads.