Here are a few apps that will help you do editing.
SPLICE- this app is great because it will let you re-size the video (zoom)
TILT-SHIFT VIDEO- this will let you blur out the outside edges of the screen, change the contrast, and brightness.
Then of course, you'll need iMovie or Avid (now called Pinnacle)
You'll need iMovie or Avid if you want to sync a sound recording or do precise edits(zoomable video waveform)
Also, iMovie will allow you to 'rotate' the video, just pinch and twist. This is handy if filming with iPhone or iPod in vertical mode.
If you want to adjust the video in splice or tilt-shift, wait till the end of the process, i.e. output from iMovie or avid in 720p, then open that movie up in the other app.
If you have any problems just message me.