Aerial and Speaker Questions

Hello all,

I've tried searching but had no joy, maybe I'm not using the right keywords...

I'm looking to upgrade the speakers in my 2015 C4 Grand Picasso. Could someone please let me know the sizes needed, do any need to be thinner in depth, are there any fitting guides?

Also I need to fit a stubby aerial to be able to fit the car in my garage, is the roof aerial for FM/AM only or is this also the DAB aerial? Hoping the DAB aerial is somewhere different.

Appreciate any help!!

Thanks

Alan