Welcome! The Z you are looking at (2011, red) is a good choice.
As for the aftermarket head unit, there are plenty of options if you search, many people go with Kenwood.
If you check the audio/visual thread of this site, you should be able to find a lot of threads answering those questions.
Also, you can check this thread:
Need Help? Let me know! of user Bigaudiofanat he does various audio builds, and im sure he can direct you in the specific equipment you need. Just shoot him a pm, and im sure he can answer you as soon as possible, or he may see this thread and chime in.
Good luck! and use the search function!
