7 segment display orientation problem
So for the 7-segment display, simply re'number' the segments connections a..g to correspond to the new orientation and change the wiring to suit. The pin that goes to the 'f' segment in normal orientation becomes 'c' and so on. 

Of course the digit commons will be flipped left-to-right if it's a multiplexed display, and the decimal points will be at the top left rather than the bottom right so other changes may be necessary. 



Your second question is unrelated, but there are industrial adjustable voltage relays that can be used for this purpose (to cut power when voltage is too low or too high).