Um, it sounds like you're doing just about everything wrong. With AE, you need to walk before you run, you have to know the basics before you can do ANYTHING of substance, and it appears you don't have the time to learn the basics. And no, there aren't any hard-and-fast answers to a situation where you need just a couple of simple things. What you think could be simple may not be in AE terms.
Do you even NEED to use AE? Why can't you use a video editing application, which is far easier to figure out?
After Effects is not created to play back a video stream realtime. It is not a video editing program.
Go to the link Mylenium gave you. It shows how to preview correctly in AE and a LOT of other things.