There is a small slot in the facia at the top of the ashtray opening (same for each ashtray drawer) and I used the slot to pass a single small screw that goes into the new part to secure it. I also added a leg at the bottom of the new part as a support. The end of this leg rests against the facia to support the new part. The surrounding edges of the part fit quite snugly against the facia, so for my needs the part is well supported. Others may choose to run a bead of slilcon/polyurethane/hot glue around the rim of the part (back side of the facia) to make the part very strongly fitted or permanent.
The entertainment unit is a Dasaita Android based unit with 10" lcd screen.... So, basically a tablet made as a car computer/entertainment unit. Pretty well anything that can be run on an android tablet can be run on this. It has a suite of apps preinstalled (including am/fm radio). I recently fitted a wireless remote steering wheel button gizmo so that I can control volume, tracks, phone from the steering wheel. The whole setup works really well.