asp.net: what's the page life cycle order of a control/page compared to a user contorl inside it?

You should look at this ASP.NET Page Life Cycle Overview and this

Page: PreInit
Control: Init
Page: Init
Page: InitComplete
Page: PreLoad
Page: Load
Control: Load
Page: LoadComplete
Page: PreRender
Control: PreRender
Page: PreRenderComplete
Page: SaveStateComplete
Page: RenderControl
Page: Render
Control: RenderControl
Control: Unload
Control: Dispose
Page: Unload
Page: Dispose