You can modify the "CrossHair with Axis Labels" sample code and apply it to the FinanceChart. Basically, you code and iterate the main chart and each indicator charts in the FinanceChart, and draw the crosshair cursor.
If you need an example, would you mind to inform me which programming language you are using and the GUI framework (such as C++/MFC, C++/Qt, C#/WPF, C#/ASP.NET, Java/SWING, etc).
To change the height of the indicators, you can use mouse up/down/move events to detect if the user has drag on the border between the indicators. Then you can raise a "ViewportChanged" event to redraw the chart with different indicator height. The exact code structure depends on your programming language and GUI framework.
Re: How to show the value in Y axis like my post and how to using mouse change the height of MACD indicator?