More to the point, I want to know if the level of the enemies in a mission are going to be higher level than I am? I usually play stealth style and rely on sneaking up on enemies for silent take downs. But if an enemy is higher level than I am I can't do that. So is there a way to know in advance if I'm under leveled for a mission?

I think it tells you street cred requirements but I'm not positive. That's generally a good way to see level requirements.

If you highlight a gig on the map, it spells out the danger level for you (easy, moderate or hard). As a rule, moderate is doable (depending on your approach) and hard, while still doable, is an irritating grind (you'll be barely dealing the enemies any damage, while they can kill you with 1-2 hits).