Does any of the functions on ur original head unit still work? Like the dsp, the time and date setting? And th rest?

I have the same car in estoril blue with factory Navi and dsp, what do you recommend if I want to keep factory for a while? Bluetooth retrofit? Aux retrofit? Screen replace? I also like to replace stock speaker with bsw speaker and subwoofer ( if I can find them) do you think I’ll hear improvements?