AEs/Single Element Queues/Data value references

I will have my CLD exam in December, and I just try to "pump up" as much as info as I can from the forum, of course beside the preparation materials...

I also started to read nice and interesting "nuggets" too, and I hope I can get some clarification for some of my questions which emerged. (Sorry if I a question is too noobish, I try to practice for the CLD beside my regular daily work load, and I am a bit slow thinker in the night )

I often use FGVs (and ActionEngines) in my applications, and during some "surfing/learning" on the NI discussion forum, I have found this post:

http://goo.gl/Cz1d0p

Here the people recommended that, the OP could use wrapper VIs which method has 2 benefits, explained here:

"Wrapping It Up"

http://goo.gl/J4vEIE

My 1st question:

I am not really sure what a wrapper VI means? Is it a subVI, where the certain AE subVI is called dynamically? I could not find examples showing how to do this (I read through the entire post, but the later discussion was more about OOP...)

2nd question:

In the second community nugget post, there are some closing notes, one of them: "AEs do not require a While Loop." I thought AEs also must use an uninitialized shift register to store info (like FGVs), and I need a while loop to have shift register...No?

3rd question:

I fall in the usual dangerous trap, which is jumping through different linked posts, and trying to understand all at once   But I wonder if out there exist some kind of basic example, which shows three solutions (ActionEngines, SingleElementQueue, Data value refs) for the very same task?

Thanks very much for explanations!

ps.: sorry for using the google shortened urls, but the forum site gives me error (please enter a valid url) when I try to paste the normal URLs...