Yes. But your wii nand will have a lot of content moved (not copied) to wiiu. If the wii has been homebrewed with a recent nand backup, the backup can be restored after the transfer so the content will stay on both consoles
Restoring an Ohneschwanzenegger nand will virginize everything except for potentially 2 things.
If bootmii installed as boot2, it will still be there after using ohneschwanzenegger.
Also, if u used Korean Kii to remove the Korean Key from a wii...
that makes no sense. if bootmii boot2 is installed, run the hackmii installed directly from an exploit (or via bootmii's mini SD launcher to boot the bootmini.elf version of the hackmii installer) and uninstall it, no need to also install the hbc...
Generally yes, except if u go restoring a nand backup it will restore the wii back to the state it was when the backup was made (excluding bootmii boot2 if installed it will stay installed), so if u proceed with this approach the end result will...
Make sure GC games are checked in the view filter setting. It's one of the buttons near the top left of gx's main menu
Also double check gx's path settings for GC games and nintendont