It's just a quick mod i'm doing for fun, and once this part is done i shall work on fleshing the whole thing out, so it might be worth release.

But for the moment, i'd like to have ghouls enter a cell, constantly. The figure would have to be capped, but i'd like atleast 15 at any one time, and them to be constantly pouring in and attacking the player.

I have no idea how do to this, but i'm guessing i'd need to create an alternate cell and fill it with monsters, and have them enter the room. But is there a way to make them instantly spawn when killed? And could i up their perception to the max so they spot the player on entry to the cell, instead of hanging around the door.

If possible could you please walk me through what i have to do, i have no experience with monsters.

You can give them an AI package set so they chase after the player (e.g. find: player, location: your cell).
To get them to respawn infinitely, you can use http://geck.gamesas.com/index.php/ResurrectActor, http://geck.gamesas.com/index.php/GetStartingPos and http://geck.gamesas.com/index.php/SetPos to bring them back to life and move them back to where you placed them in the editor. You'd need to put a script on them that checked when they were dead, then waited a while (or made them fade out using http://geck.gamesas.com/index.php/SetActorAlpha) and reset them.
Continually spawning new creatures rather than recycling existing ones would start to slow things down pretty quickly.

Just an example of the fade-out script- as alpha goes from 1 (fully visible) to 0 (fully invisible):

float timerfloat FadeValueshort isFadingbegin ondeath   set isFading to 1   set timer to 10endbegin gamemodeif(isFading)   set timer to timer - getSecondsPassed   if(timer > 0)      set FadeValue to timer / 10       setActorAlpha FadeValue   else      set isFading to 0      ;they've fully faded out now   endifendifend

Could i perhaps have a more in depth explanation? I really have no understanding of how this works, and i'm usually afraid of changing the wrong setting to try and work it out.

I don't know if respawning a monster would force his body to disappear? If so;

I'd like for say, 25 ghouls to be in a room in a cell. They should be scripted so that from spawning, they enter the door into my main cell, and attack anyone. When they are killed, for their bodies to stay on the ground for say 30 seconds, and then be respawned back in the room in the cell, and re-enter and attack.

If bodies can stay on the ground after a new monster has been spawned then i would just like for about 15-20 ghouls to spawn, enter and attack.

I could provide the esp. if you would like? I'm prone to making unfixable mistakes in the geck.