If you erased the find my iPad app can you still locate it?

Of course, but only if Find my iPhone is turned on in Settings > iCloud. Note that the Find my iPhone app is only to track other devices with Find my iPhone activated, not to be able to track your iPhone, iPad or iPod touch.

You can track the device from any computer in http://www.icloud.com. Log in with your Apple ID and select Find my iPhone

No, you will need that app install and signed in to your Apple ID.