DAB converter questions (Power Electronics)

Hi, I have an hw that is on the topic of Power electronics. It is about DAB (Dual Active Bridge) Converters. If you know DAB they are very easy. It is basically extension of some lecture notes. I have uploaded the lecture notes online so you can check them. They are here

http://imgur.com/a/Bp9ND

The following are the questions to be answered.

1. Derive both forms of equation for the output current from Pg.5  (Eq. 7)

2. Find the output power for the case when on the right hand side is a voltage source

3. Find the output voltage for the case when at the output there is parallel C-R combination

4. Plot how the output power changes as the phase shift changes from -Pi to +Pi (for two voltage sources case)

5. What it the angle that results in the maximum power flow and what is the power in that case?

Thanks