What is FP? Regarding your question about the number of man-hours: that totally depends on many factors. For instance the number of use-case and the complexity of those, non-functional use-cases; such as the number of users (there is a huge difference between one and 10.000 concurrent users) etc. It can't be said based on those simple numbers you provided.
"Any fool can write code that a computer can understand. Good programmers write code that humans can understand." --- Martin Fowler
Please correct my English.
FP is Function point, a metric for measuring the expected complexity of software, which can then be used as a way of estimating the time it will take to develop.
I must admit, I'm fairly sceptical myself. But then, I'ver never used it either (or known anyone that has).
In terms of using it to predict development time, though - as I understand it you're supposed to use it to compare with the complexity of completed projects that you know the development time for. Productivity varies so much that you can't use a standard set of numbers to compare it against: that could feasibly give you an industry standard estimate, but not an estimate that is going to be useful for yourself or your own organisation - which is what you really want. So the next step would be to start gathering data from other projects.
Calculating productivity highly depends on the team producing the result and the quality of the result required.
So a sensible thing to do is to determine what you consider to be the definition of done of a certain task and what the velocity of your team is.
To have more info on this : 'velocity' and 'definition of done' are concepts from scrum