Hi,
In general you can find most of the components you need in the library, however if want to design special one you can do it either by C++ or matlab and insert it in your design. many examples for Matlab co-simulation are there in OptiSystem 15.
regarding you questions:
1. yes CW laser can be working as a tunable laser source whose operating wavelength might be either fixed or sweep for certain range.
2. there are examples might help, I encourage you to have a look at the examples included.
Hope that helps,
thanks
Mohamed Abouseif