You're right about the mercenary structures. It's something I simply didn't think about. For the test I'm gonna set the price of switching and buying new merc to 750. We'll see how this works out.
The Laser Snipe should be done manually, auto-cast would be too easy and of course, too strong.
In a game with 8 players, it is very unlikely that nobody has anti-air units. Good players should know that air units are popular and thus have decent counters at hand. We will see the problems when we're testing.