1. : If no router, then nothing to forward and therefore you can skip part 1.
2. : Seems right, exept you have to change what ip the server should use when in passive mode.
You have marked "default".
You should mark "use the following IP" and inset you ip, if you have static IP.
If you have dynamic IP, and you say you do, then mark the "retrive external ip adress from"
3. : Your entrys in Comodo Network monitor looks fine.
Server internal IP dosen´t matter if you have no router. If you had a router you would have one IP seen from outside and on the inside your first pc would be 10.0.0.2, second pc would be 10.0.0.3 and so on. If you were running the Filezilla server from, let´s say, pc2, then you should enter 10.0.0.3 as server internal IP.
Since you have dynamic IP you shold set the destination IP in both rules to ANY.
Or else you will have to change the IP setting in Comodo every time your IP changes.
This is all it takes to get FileZilla server to work with Comodo Firewall.
If your frinds still can´t connect then maybe you have made some bad settings in FileZilla.
Did you remember to give access to the folders they are supposed to use.
When you make new accounts, you will have to grant access to a folder that will be this user´s base-directory. Inside this folder you shold make at least 2 folders. 1 download and 1 upload.
All 3 folders will have to be added under this user.
In Base-dir and download folder you should mark "read" in "files" and in "directorys" you should mark "list" and "+subdirs"
In upload folder you should mark "read","write" and "append" in "files" and in "directorys" you should mark "create","list" and "+subdirs".
Now this user can open and browse all 3 folders, download from "download"-folder and upload in "upload"-folder. But he can´t delete anything, only you can do that.