How can I uninstall applications that are locked by phone vendor?
Is it possible to uninstall stock Sprint apps (such as Sprint TV and Nascar) without rooting the phone? If so, are there any undesirable side effects?
Depends on your definition of 'rooting'. Depending on your phone, you may be able to simply install a custom Recovery on the device, boot to that, and either manually remove the apps through the adb shell or using some sort of installable script fed through the recovery in the form of a .zip file. (That's how it works on the Samsung Moment. Again, not sure what device you have and what options would be available in the custom recovery of that device)
The custom recovery will give you 'root' access to remove what you need to remove, but it will be separate from the regular Android, which will in no way have root. So if you're worried about the security risks involved in potentially allowing other apps to gain root access, that's not something that could happen with just a custom recovery. However, if you're looking at it from more of a warranty standpoint, and simply don't want to make unauthorized modifications to the phone, well, not much that can be done unfortunately.
No. Sorry. Anything "System" cannot get uninstalled without being root. Some apps like ADW.Launcher allow you to "hide" them by making app groups in the app picker list. These apps will still start during boot, but like all android apps, as long as they are not running, they won't consume anything other than ram, and if android needs more ram they will be the first things just removed from ram the second the phone needs it.