If the price of bitcoins goes up, there will be a (not in nominal, but in value i.e. in gold) profit.
Admittedly it would have been a lot easier to just buy bitcoins to make that bet.
Edit: there is also another upside: mined bitcoins are truly anonymous which can motivate a premium in high-friction transactions..
It is true if you mine it yourself. Not if you are part of a pool.
As for the profitability, I suggest that you have a look at this site:
http://www.coinish.com/calc/#It, finally, takes into account the increase in the difficulty.