How to rebrand/copyright a forked project (GNU/GPL)? [closed]

Question

long story short, we're forking a free software. The code is under GNU/GPL license, we've tried to collaborate with the original developer but without success. We're improving the software adding a lot of features and unlikely our code will be merged in the original one.

We want to call the new project with a new name, use the same license of course and change the copyright notice in every file.

I know it should be allowed by the GNU/GPL to modify the code and redistribuite but here some questions:

1. Is it OK to change the project name? (I guess yes)
2. Is is OK to add our copyright notice and remove the original or we should just add our and leave the original copyright notice?
3. We have to leave the reference to the old project in the code? (In the header he asks to make a reference to his project/website in case of fork. I guess it's just a suggestion and we could not do it, right?)

Answer 1

1. Sure. In fact, not changing it at least a little would imply it's the original project, which is a bad idea.

2. You can't remove copyright notices. Add yours on top.

3. Why do you want to remove the reference to the old project? It's a suggestion, but removing it would be impolite and potentially misleading. The Open Source/Free Software communities value correct attribution.