I am not sure if ePSXe will load m3u files. I just did a quick test of it and it did not work, no idea if it was something I am doing wrong or not. I don't use ePSXe extensively, I only use it on my other, lower end PC that isn't fast enough to run the Retroarch core for Playstation.
For disk management in Rteroarch though if you go into the quick menu with the PS core running you will see near the bottom an entry for Disk Control. In there you can open the tray, change disks and close the tray when the game prompts for the next game disk.