Interesting about the side shot. Haven't used it that much so I didn't know it made the first loop easier. I take back shot and find myself having to be more aggressive, which is both good and bad up to this point. I'll probably stick with it though.
I get a fair amount of mileage from charge in loop one, but after reading the no time to charge thing I may start experimenting with homing shot. Which should be funny cause I usually abhor any type of lock on shot in any game.
I take the drill too although I don't know the difference. The shield that builds with your multiplier is a big help. And thanks to Rue's post I've had some minor success building the multiplier up to 12.8 with melee and then keeping it there with other weapons.
That said I have noticed:
Spoiler
Also the heads in stage four - I use the charge shot followed by regular shot. I tried to melee them but those fuckers warp away if you get too close.