How to drill and waterproof a hole in cinder block for PVC drain?
Your instincts sound right. Be sure the drain tube is slanted downward as it exits. Also be sure the outside end of the tube will not be blocked (by leaves, snow, etc.) and that there is adequate drainage away from the outlet site. The ground should be pitched away from the wall (as in every foundation).

The likelihood of rebar or wiring within the cinderblock is very small. To be certain, go slowly and inspect with a light as the pressure changes in drilling. There are hollow sections in concrete and cinder blocks and you should be aiming for those, rather than the webbing between holes. 

Sealing should be done with a weatherproof cualking on both inside and outside.