Video Editing Issues

I use iMovie to edit videos. They are typically 2 hrs in length and I draw from about 16 hrs of footage.

For my current setup I use an external HD because the raw footage won't fit on the internal.

I have a lot of issues... With audio/video sync, once I load the clips into iMovie they all seem to be off. Also, it takes forever to load footage into iMovie (like several hours), and finalize/export the finished product (overnight).

Is this because I'm drawing from the external HD? (I put the iMovie events and iMovie Projects folders on the external HD.)

Should I get a bigger internal HD to solve this?

**If anyone else feels like throwing in any other tips I'm all ears! I'm an amateur who will grow, I have just been learning as I go.**

Thanks!

 

Do you have a recommended internal HD? Or just anything will do fine...