Modifying existing cockpit layout


I'm new to these simulation environments and I'm doing a little pre-examination to determine how to continue from here.
So what I would like to know:

If I get the Prepar3d simulator and the development kit for that, is it possible for me to modify existing cockpit layout?
For example if some cockpit is updated to have new instrument and I would like to add that to some existing model, is it possible?

If there are displays in existing models cockpit, can I change the displayed data when some button or switch in the cockpit is operated?