As far as I know you'll still need to convert them, yeah. I use a tool called Gamecube ISO Tool, which can be found here. To use it, load the program, then click File > Open ISO then select your .iso or .gcm file. Then, do File > Extract > DiscEx Format (GCReEx may work too, but I've always used DiscEx), and tell it where to save the converted files. It should give you a folder with the games name, containing a game.iso file and some other stuff. Stick the whole folder somewhere on your USB device.
As for loaders, Wiiflow usually works for me, though I do still have Dios Mios installed so I'm not sure if this particular loader needs that. You can give it a shot anyway, and can find it here. There should be a fairly easy to find option to look for GC games, IIRC it'll be a button with the Gamecube logo on it. If you click through that and can't get it to see your games, try sticking the USB device in a different port and try again. If they still don't show up let us know here.
"I think that the problem with this video is it is highly derivative of many popular bands within the genre. Although when viewed on its own merits, it does have a deeper groove. However what it has in groove, it lacks in originality. One can't help but be reminded of such bands as Pearl Jam, White Zombie, Suicidal Tendencies and other bands that bear the mantle of so called "Alternative Rock". One is even reminded of Lorie Anderson when she wore curlers. Hehehmhm! This video speaks less to the heart and more to the sphincter. In closing, I think Korn would do well to learn more from -"