1. yes the loader is just a tool to find the games, so every usb loader will find whatever games are on your drive.
2. Original discs can be played from the disc channel. Backup discs (If your Wii is old enough to play) would need to be played from Neogamma. And with the block disc updates hack enabled, they will not ask for updates.
3. I don't own Skylander, so I can't really say (I do need to get it soon, since my daughter loves Spryro). I would ask in the guide, if it doesn't already explain it.