You don't get the exact same number of eggs you hide - there are quests that ask for you to hide eggs, giving double eggs of what you hide. They start off easy - 1, 6, 12, but slowly the number raises and they stop after a while. The final quests ask for you to buy EACH of the rewards at least once and rewads you 250 eggs in exchange. The eggs you collect in your own city however, give you a random number of eggs (1, 5, 20, 50, dunno all the numbers) so if you're lucky you can get more eggs from a lower number of collections.
Regarding the rogue - as LacLong said, they're easy to kill off with both long range and short range. Plus, they can't kill most units in one turn (remember that units in upper ages are more powerful, especially if they have GB boosts), so they would turn to another unit after they use their first hit. Then, if the rest of your army was just long range, you'd get long range units next to the enemy's units. Not so good, right? Even if your army is a mix of more units, it could turn to the unit you least need and is easiest to be killed by the enemy's troops.
As I said, very powerful unit, but it requires both strategy and luck to use it wisely.