I enjoy playing combat medic, the style of healing is awesome and the fact that you can still DPS when you have some downtime from healing is cool also. though for a companion i would recommend Dorne, if you are healing and the droid is tanking, no one is left to DPS. also he is a bit squishy in hard fights. I have found Dornes healing is sufficient enough that I can focus DPS while using heals in between to keep myself topped off. But if you are dead set on having a tank companion, put in vic. he is a little less squishy, and doesn't require hard to find machine parts to keep up.
as far as crew skills, I have cybertech, scav, and slicing (I have 2 guildies with UT) and the machine parts become obsolete relatively quickly until you get orange ones. but all in all any crewskill that seems interesting will work, though maybe not synthweaving and artifice...