i currently have an htc tattoo and will likely be getting an htc desire soon, will i need to rebuy my apps or will they just transfere over (redownload without paying again) when i log in my google account.
Paid apps can be redownloaded, with the same Google account of course. Free apps are obviously free and can still be downloaded for free. However, none of your app's settings or data will be backed up. To do this, you would have to root both phones and use Titanium Backup.
CoPilot can be quite fiddly - you need to deactivate the app from the settings menu before switching over to the new phone.
You will then need to go through the activation procedure again on the new phone, using the codes they emailed you.
If you hit major problems, contact their support - Android is the only platform that they explicitly permit moving licences between devices. It does work though - I've done it once and will be doing it again later this year when I upgrade to my next phone.
Some apps don't save progress or settings to the sd card, most seem to save to /data on the internal memory which can't be ported over unless both phones are rooted and using an app such as titanium backup.