Can't advise either. Not an expert in car audio system and will never be, only because there are roughly 7,233,888 different options out there to chose from. All preety elementary stuff however thank god lolll Whateverworks for you man
On the safety part, ensure that the amp is positioned/oriented as-per-mfg-advice. That to ensure proper heat management. Some can be held vertically, input facing top, others needs to be flatten, etc etc. 3x make sure of this with the manufacturer (400x4 amps can become quite hot in summer days...). Careful with that.