I'd say "yes, coolant for aluminum", and "no, dry for steel". I just find that often I don't get good insert life when using coolant on carbide when cutting steel, so I run it dry with air blast to move the chips.
There are so darn many grades of carbide out there now, there may be something that can tolerate thermal stress/shock that I don't know about. I usually keep a stock of moldy old inserts on hand, so I may be well behind on the latest and greatest insert grade.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)