>Can I do this with out messing with the leveled enemy lists? Just place my enemies in my world at will?
Yes! You have several options to do this. If you are fine with the default drop rates/enemies/etc that you get in Skyrim, it is as easy as drag and drop. If you want to tweak some things (i.e. adjust spells on an enemy, adjust inventory, adjust how they level in relation to the player such as making Giants minimum level higher or lower than it is in skyrim), then the best course of action would be to duplicate the enemy in the object window, rename it, then make the changes you want. Then use those objects to populate your world. That way you aren't overwriting the default Skyrim enemies, and you are free to make changes at will to the references you place in your worldspace.
>What's the difference between ENC enemies and LVL enemies?. why do ENC enemies appear as models in the render window and the LVL appear as green "M's" in the render window?.
For what I understand the LVL are random Lvl'd enemies that will spawn according to the character's level, these spawns are controlled by the Leveled Enemy Lists and ENC enemies are concrete mobs which LVL is not controlled by the character's LVL.
Close. LVL enemies are enemies that take from a Leveled List. A leveled list is a list of potential enemies that can spawn there, and usually vary in difficulty based on the player level. For example, a LvlBandit1HMelee marker will spawn a random enemy that is from a Bandit1HMelee Leveled List. The leveled list is just a list of Enc style enemies. Sometimes these are level restricted (i.e. a bandit in a level list that is restricted to only spawn past level 24 might spawn with higher level gear, while a lower level bandit from this list would spawn with lower level gear). But sometimes they are simply variations of the same enemy but with different abilities.
Enc enemies are specific enemies. Such as if you want specifically a skeever or frost troll to spawn at a location, you would use an Enc enemy for that. You wouldn't use a Lvl enemy because the game isn't sure what that enemy is until the cell loads, and it could technically be anything if the leveled list you are pulling from has multiple types of enemies in it. LAmbientCreatures for example can spawn either foxes or hares. If you wanted specifically a fox, you'd use an EncFox.
Both Enc enemies and Lvl enemies can be tied to player level, or restricted to a specific level. It depends on how that enemy is set up. They are both the essentially the same thing. Just that Lvl enemies pull from a list of potential enemies (usually that differ based on your level, i.e. the higher level spawn will have different things than a lower level one) and Enc's are a specific enemy.
>Can I set the respawn rate? I want them to respawn every 24 in-game hours. I know there is a way to configure this, but it does it for the entire game, I don't want that. I just want to do this for the enemies within my world.
I've not personally tried to do this, but I'm pretty sure you can. If you want to do it independently of Skyrim's normal respawn rate you might have to hook them up to a hidden quest to handle all that. But that doesn't seem too efficient. I'll let someone else chime in.
>Regarding World Hook up. I want to travel to my world using an NPC. There is a famous mod called Wyrmstooth that has an NPC that can take you to Wyrmstooth and vice versa from Wyrmstooth back to Skyrim using a dialog branch "take me back to skyrim". I want that. how can I do that?.
Look into the Dialog tutorials on the Creation Kit wiki. It explains how to set up text conversations and tie script events to them. I suggest looking at Wyrmsooth to see how they do it specifically, but I imagine it involves tying a simple MoveTo script command to a dialog choice.