Retopology and rigging of clothes for games

As I’ve slowly been building my game creation skills I have inevitably hit the clothing wall. Now I’ve started learning marvelous designer and for the most part it has been a relatively nice experience but then came the implementation part and I’ve been stuck for multiple days not knowing what to do so

Question #1: I have a general idea of how to retopologize single pieces of clothes fine, but when making a game character that wears multiple layers of clothes like suits, jackets, etc. do you retopo each piece individually or do you retopo once over all the layers when the model is clothed.

Normally I was like “no you retopo each piece individually” but then I thought to myself but in games 99% you erase the character model beneath the clothes to avoid clipping and save memory so why would I retopo the shirt that’s nearly covered up completely individually?? But then I thought “maybe I retopo each piece individually and do like the base mode (cut under the layers to avoid clipping and save memory)”

Over all the question has been plaguing me for days and hardly any questions were asked about it

Question #2: how do you go about cutting and rigging the model with the clothes instead of the body??

To my understanding and I’m not sure if that’s true so please clarify if I’m not.

-I grab the head (for example) and select a certain edge loop that goes under the shirt then cut and delete under it, same with hands. -I then start rigging and adding the bones as if there IS a body just making sure that the gaps between (cut body) and clothes don’t appear in animations.

Is that it?? Did I miss something?

If I didn’t then what should I do about question 1?? is it the same with question 2 (cut under the layers to avoid clipping and save memory)?? And if so then after all is done should I attach all the layers together?? I heard some people say that combining meshes and having one Fully attached mesh is better for saving resources but it seems heavily time-consuming, restrictive, and overly complicated to attach everything after it’s done.