A little search function came up with plenty of answers for your questions.
Layer Break:
To Layer Break or not to Layer Break, That is the question!
So for D2CKey -> Yes
How to manual layer break with IMGBurn posted by me
New to burning Wii ISOs. Need help and tips.
Discs brands: Depends on your Wii. Many have had success with crappy media like Memorex. My one good copy is on a Verbatim.