I just happen to try PSX ISO recently, and it mounted the img & bin file quite well, however it can't seem to read/run these "7z" files dl-ed from here though, what the deal with these files anyway?, are they not the same with img/bin?
No they're compressed archives like zip and rar files, you'll need either 7zip or winrar to open the files.
Problem is, even If I can extract/open them, my PSX emulator couldn't read/run the file, is there any way to convert them to .bin or .img somehow?
no, 7zip is an archive, the .iso/.img/.bin files are inside the 7zip. You must extract the files and the extracted files are readable by ePSXe
Ah..., how silly of me, misinterpreted what you guys mean until a moments ago, thanks for the clarification, now my only problem left is only the yet unreadable .nrg file until I figure it out.