Must, have to ?

I've been searching quite some time to find it out that in the assurance meaning 'have to' and 'must' can be changed to the tenses.
The result is, for must there are 2 possible tenses(present,past) and the only one tense(present) is all I could find in lots of searching for have to.
i.e. He has to be the worst actor on TV!
Your trip must have been fun / This must be the scary picture I've ever seen.
What makes me wonder are the following questions,
first, Is it possible for 'have to' to have a future time or a past tense still holding on the meaning of assurance?
i.e. It will have to be the big party / He had to leave earlier than expected.
and second, about 'must have to', what is the exact interpretation for this meaning-overlapped looking expression?