I have been practicing samatha for five years now and have rarely done any other kind of meditation.I have tried to practice vippassana in the past but get confused with how to do it.

1.First of all you place your attention on your abdomen,when i'm more used to my attention being on the tip of my nose.Is there a way to practice vippassanna with your attention on the tip of your nose?i can avoid getting too concentrated with a technique i found by accident,by widening my focus to the entire nostril instead of just a point.This helps allow for thoughts etc to arise.Because I notice during samatha thoughts are minimum to none.

2.Please describe a method of practicing vippassanna with the base/anchor being the tip of the nose not the abdomen.

Many thanks.