Can Sir Lamorak when using the "lose one life point" for the progression of evil phase prevent the life loss by using his special power?
and if so can he also use it when he loses a life point to do an additional heroic action?
No & no. Spending a life point is a different from losing one.
I know it's been clarified somewhere, maybe by the authors themselves, but I don't immediately recall how I got that. You'll just have to trust me on this, I guess...