Please Recommend a video editor

I have several videos which I plan on editing then hosting on a public site.
But the videos need some tweaking before I upload them.
Thus, I am looking for video editing software that can do the following:

1.) adjust brightness of the video (I assume this can be done just as adjusting of brightness and contrast can be done to single frame (individual photographs) - do you know if something exists that can do this to multiple frames (an entire video)?

2.) easily crop the length (easy to set start and finish frames in real time)

3.) overwrite or replace the audio channel

4.) accept input format MPG, and produce output format MPG

Other than that, would like it to be extremely user friendly, don't want to have to invest hours of time just to learn how to use something for such simple tweaks. And preferably of small size (under 500 MB), and runs very quickly (when doing something like brightening the video). Free would be nice, but not necessary, am willing to pay up to a few hundred bucks if it has all features listed above and I can use a trial version first.

Can anyone recommend something?

Thanks

Thanks Michael, I might give that one a try next; Does it have a feature which allows one to slow down or speed up video footage? Thats another feature that would be nice to have.

I found a very good (and free) basic editor which has the features I was looking for initially (listed above), including the brightness adjustment. Its called VideoPad Video Editor by NCH Software. Though it doesn't have slow motion capabiltiy and I want to try others in order to compare.