Yes, I just took a look at the Pinnacle Studio forum and found that there appears to be no support happening there. I'm sorry about that. Our contract to develop and support the app ended. Although Chris and I were the original lead developer and designer, the app was never owned by us and we were not able to make the changes we needed to make to propel the app forward. Pinnacle Studio was not designed to take on the challenges that advanced editors face. It is one of the reasons we have developed our own professional editor, LumaFusion: http://luma-touch.com/lumafusion-for-ios/
The answer to your first question is that with Pinnacle Studio there is no track sync and no Insert/Overwrite mode. Basically the video track works in Insert and the audio in Overwrite. Insert/Overwrite control is what you will need to do that.
The answer to your second question is no. The only way to do that with Pinnacle Studio is to export each and then put them together as clips on a new timeline.
I hope you are able to find support for Pinnacle Studio, or join us with LumaFusion, where we give daily free support.