Do not worry about kundalini. As to depression, this can be caused by a variety of factors. See if your depression is caused by a particular problem. I am familiar with nadishodan but not with the others. It will be hard to explain over the email, but i will give it a shot, but if you have some yoga book then look in there to double check.
Emphasis is on exhale, inhale is automatic.
This exercise cleans and purifies the head area. Start with 3 rounds and increase over time. Either concentrate on ajna chakra or visualize energy moving up the spine upward. Do as many as possible then increase over time. Start with 3 rounds and increase later.