BleepingComputer.com: How To Use Sony Vegas Pro 8?

Ok,I'm have to many question already,lol
I try using it since WMM 2.1 cannot bring back to life
But,I think I use it wrongly

[problem no. 1]
First,when I save a 20 minutes video(to correct the audio sycn problem) in AVI format
and it save it in 6 gigabyte
and nearly crash the whole comp
I delete it again and try MP4 format,it works,but i prefer AVI format

[problem no. 2]
How to split video in the media bin or something like that?
NOT in timeline!!

Hope you can help me!