If the remote sensors require power, and are going to be more than a few inches
from the Arduino bd, you really want to have separate v.regs near the sensors,
plus filters/bypass capacitors. It's generally not the best idea to run 5V regulated
power over long wires, and expect everything to still work well.
Some v.regs have over-current and thermal shutdown ckts inside the parts, but
you need to check the datasheets. Surface-mount parts may be less robust than large
TO-220 parts. Also, some v.regs fry instantly if you hookup Vin with reverse polarity,
while the old LM7805s can handle it better.
However, if you use the Arduino to sense the load current of the sensors, as indicated
previously, then you can shut down the power to the sensors in case of shorts.
The 3N3055 is a high power transistor, but you really don't need such a part for a
few mA for sensors.