Extend functionality of b2ctelcoaddon

Hi all,

I am using Hybris 6.7 Accelerator. I want to extend an AddOn called b2ctelcoaddon. The general approach I have read so far is to create an empty AddOn and add a dependency to the Out-of-the-box addOn. However, I have a few questions:

1. Is the above approach correct?

2. When I create the empty AddOn, should I copy only those UI-specific files(JSP,tag etc.) to the custom AddOn which I want to modify?

3. If the out-of-box AddOn gets changed in a future release, would it impact the custom AddOn?