Yet more interior questions

[eighteenninetytwo]

Apologies for practically monopolizing the forum over the past couple of days with questions, but I'm going to try to get a ton done this coming weekend and want to know stuff in advance.

Q1. Has anyone used a sound deadener (dynamat) THEN a foam decoupler (think dynaliner) THEN Mass loaded vinyl under a carpet set or is this too excessive and heavy?

Q2. Does anyone have (or could take) a picture of how and where the vinyl trim that fits by and over the vent in the passenger footwell attaches. There are two pieces and I took them off two years ago, but I cannot remember where exactly they go back.