[LE] HOW TO EDIT EXISTING NPCS USING MOD ASSETS?

[FriskyAlpacas]

I'm a complete newb at this, so please bare with me and I do not wish to use the mod called NPC editor, so please don't respond with that.

Let's say I want to edit Faendal's appearance: Skin Texture, eye color, and hair

Using the following mods: Fine face textures for Men or Vitruvia , Natural Eyes, and KS Hairdos Renewal

How would I go about doing this?

Can anyone provide a step by step?

I've got creation kit installed and I know I need to convert the esp files into esm files, but I'm not sure how to do that or how to make it so the changes I make in CK reflect in game.

If I need Wrye Bash how do I install it with NMM?

Also, I've read that there's a way to create NPC/followers using Nifskope, Creation Kit, and Racemenu, but does that process work with existing NPCs? and can you still use assets from other mods if you do it that way? If so, how is this done?

Note: I'd like to be able to still use SOS so I don't want to make any changes to the body other than maybe texture. I've been trying to use Males of Skyrim with Schlongs of Skyrim and it just creates a double nightmare below the waste and when I went into Tes5edit to remove the armor for Males of Skyrim my game just started stuttering and crashing.

Please and thank you in advance!

There's all these NPC overhauls and NPC replacers available like the Bijin series and Males of Skyrim, but not one mod author has come forward to share how they did it and it's completely baffling and frustrating.