@"Ecchi Gamer"
I suggest you stay away from Apex right now, not trying to confine you but you can do a lot with regular physics right now, Apex has complex workflow and it will require you learn a new tool which is either Nvidia's own cloth authoring tool or 3DS Max with Apex plugin and both are difficult in their own ways.
The benefit of Apex only appears when you're animating a long cloth or something like skirt, everything else can be done pretty nicely in regular physics, even long clothes can be done in regular physics if you're good with handling lots of bones and know how to rig them properly.
The main difference between Apex physics and regular physics is that Apex allow you to make each vertex move individually while regular physics make a set of vertex follow the bone they are rigged on so when working with clothes Apex give you more soft looking cloth while regular physics give you more stiff cloth, also collisions are more accurate in Apex due to all vertices having individual movement but they are hard to setup properly, in some cases more hard than regular physics.
To answer few of your questions.
1) You make APEX cloth as I mentioned above (either using Nvidia's tool or 3DS Max with Apex plugin).
2) It's merged with main character FBX when you cook your project and once compiled, it cannot be extracted.
3) Yes Apex asset is a separate file using *.apx extension, that's the file that you import in UE. It has nothing to do with your main physics asset.
4) Yes one character can use multiple apex assets, that's how I made my Laura Mileena mod. It's using two assets, one to animate her long back cloth and other to animate her belt and veil.
5) I mentioned the advantages above.
I suggest you stay away from Apex right now, not trying to confine you but you can do a lot with regular physics right now, Apex has complex workflow and it will require you learn a new tool which is either Nvidia's own cloth authoring tool or 3DS Max with Apex plugin and both are difficult in their own ways.
The benefit of Apex only appears when you're animating a long cloth or something like skirt, everything else can be done pretty nicely in regular physics, even long clothes can be done in regular physics if you're good with handling lots of bones and know how to rig them properly.
The main difference between Apex physics and regular physics is that Apex allow you to make each vertex move individually while regular physics make a set of vertex follow the bone they are rigged on so when working with clothes Apex give you more soft looking cloth while regular physics give you more stiff cloth, also collisions are more accurate in Apex due to all vertices having individual movement but they are hard to setup properly, in some cases more hard than regular physics.
To answer few of your questions.
1) You make APEX cloth as I mentioned above (either using Nvidia's tool or 3DS Max with Apex plugin).
2) It's merged with main character FBX when you cook your project and once compiled, it cannot be extracted.
3) Yes Apex asset is a separate file using *.apx extension, that's the file that you import in UE. It has nothing to do with your main physics asset.
4) Yes one character can use multiple apex assets, that's how I made my Laura Mileena mod. It's using two assets, one to animate her long back cloth and other to animate her belt and veil.
5) I mentioned the advantages above.