I hate it when an attacker grabs a turret. He then has superior armor AND superior weaponry. It is supposed to be defenders has superior weaponry but no nanosuit armor. Attackers has nanosuit armor but only pistols. All turrets are more towards the attackersd than the defenders, so they almost always get them and they dominate everyone.
1) About availability at level 18. I think PC players has it from the very beginning. 2) I hate it when an attacker grabs a turret roo, but I like it when I am that attacker : )