An LSD will help you with your angle and sustained drifts, but track time will help you more. Like Drifter S said, you will learn 100 times faster, and you don't have to worry about cops or killing innocents.
Anywho, yeah, when you let off the throttle, you've stopped the drift. Stay in it, but you don't need to be redlining.
Read up on here. A lot of good drifters have posted a lot of good information to help you get started. Don't be phased if you don't get the hang of it right away. Find a track and practice as much as possible, and if you can, go for a ride along with other drivers.
edit: This is a good read:
zerothread/132583