Is Anti-Theft really needed for my protection?

I’m a little edgy on activating the Anti-Theft to get stealth mode. I want the best protection but not overkill. If Stealth mode is activated, will my gps, wifi and 3g be deactivated on my Incredible 2? How exactly will it affect my phone?

For sure not.
Stealth mode does not change the network connections.
It just hide (disguise) the installation of Anti-Theft. Nothing more.

http://files.avast.com/files/documentation/mobile-security-user-guide-en.pdf
https://support.avast.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=1034