Having the turret lock onto a lane was something I considered but did not think I could implement in a satisfactory way, but it is something I could consider adding later.
As for introducing the gates slower, if you mean something along the line of starting with one and increasing the amount over time, I can certainly consider it. Currently the gates are only passive, having an effect on targets that pass through it, so being aware of the gates mainly provides you with a better idea of where to focus your efforts in their current implementation.