How to create a helper application for Mac App to start it on user login?

Question

In fact, I read the following document:

Applications can contain a helper application as a full application bundle, stored inside the main application bundle in the

Answer 1

I've never used LSRegisterURL, I can answer the first question: to set the LSUIElement bit you just simply open the .plist and add the row "Application is agent (UIElement)", then set the value to TRUE.