If

Hi,

I wonder how the following 'if' sentence would work: If he was going to be compared to Mozart, that would do him a world of good. (Is this right in simple past and not conditional? I am assuming was becomes is and would becomes will in present)

b) In a conversation, is this okay: You must do as the manual says, failing which there would be no valuable result.
It would help if you could do that.
(just two examples I made up, so it doesn't matter if they are good. I just wish to know whether 'must' and 'would' and 'could' can be used in this manner while speaking, which is present tense).

c) Slightly similar to above, as in conversation: I'd say you've been smoking for years. (is this right?)

Regards,