I will write down the schematics, but as a general question is there any safety measures to take when powering a sensor directly from a digital pin?
There is. Don't. It's really that simple.
Use the pin to control the gate on a transistor. Transistors need very little current to open or close the gate.
and b) if the setup kills digital pins I guess it may kill the transistor just the same?
You probably killed the digital pin by pulling too much current. 40mA is the maximum recommended. Your measurements seem to indicate that you are drawing less than that, but you haven't said exactly how you measured the current, so I tend to think that "incorrectly" is the answer.