From my experience a road crankset and front derailleur will work better with STI shifters. If the front derailler will be a "clamp-on" type (instead of a "braze-on type") you should be able to lower it enough for relatively smaller chainrings. You might consider a "touring" type crankset with 110 BCD chainrings if you want lower gearing, instead of a mountain type crankset. In the back you need a rear derailleur that has enough chainwrap capacity for the gearing combination you select. A mountain type rear derailleur will allow a greater range of gearing and will be compatible with STI shifters. The shifters and chain need to be compatible with the number of cogs on the cassette. Shimano mountain cassettes are a maximum of 9-speeds but IRD and possibly others make 10-speed Shimano compatible cassettes.
Al