My Foundry "guy" is a lvl 2 Lieutenant, and all difficulty and total of enemy ships is structured for my Lieutenant level. Is there anyway for me to bounce up to admiral rank and test the mission in that rank and see how everything works when it comes to ships and such?
If I am correct, then smaller and less enemy ships spawns the lower level you are?
There's no easy way to VA, but you do have the kill target at your disposal.
As to your other question though, your level ONLY affects the level of the enemy NPCs, not their numbers. The extra space mobs you see in an NPC group show up depending on the number of people in the group. Ground mobs all show up because even when you're alone you have 4 bridge officers backing you up.
If you want some idea of which space mobs will show up with certain group sizes, someone cataloged their spawn behavior a while back in this post: