Jailbreak apps question.

I have a question about jailbroken apps

For example, I have color keyboard downloaded. If I explore it, I can see it has themes stored on my iPhone from it. If I remove this app, does it remove everything associated with it (themes) or just remove the app.

What I'm saying is, does removing it get rid of all the memory its parts take up or is it just leaving useless files on my phone?

Also on a similar note, will a restore get rid of all the stuff stored on my phone like this?