this is one person's experience...https://www.youtube.com/watch?v=j-WTG5DMwvk
going in from the side on this onehttps://www.youtube.com/watch?v=y4jzk0XhBtI
using penetrating oil made to work with rusted parts will help a lot. you have to spray it on and wait a while. 10 - 20 min works for me. The heat shield is to keep the heat from exhaust manifold away from other parts that may be adversely affected, like your hands... Keeps the fans from blowing directly onto a hot manifold and keeps the heat from the manifold from heating up your radiator.
I think torching the cover would be bad if something goes wrong with the open flame. Using a good ratchet and making the bolts move will either free them or break them off. If they break off I would be worried about how the manifold bolts are going to be...