I posted about this on another site but I will give my view here.

When Jesus was tempted by satan,he was asked to throw himself off the temple to prove the scripture that angles would lift him up.His reply was not to tempt God.

I do believe Mark 16 literally,but I find the example of it working in Acts 28 when Paul shook off a deadly snake with no ill effect.

It is my understanding,that scripture must be interpreted with other scripture.When scripture seems to contridict it'self,you have missed the true meaning.There is an old story about a man who swore to God that he would do what he read in the Bible.He opened his Bible and read the scripture,"Judas went and hanged himself." Then he opened his bible to another place and read,"Go and do thou likewise."