If there is nobody else around. (24 hour gym, middle of the dark hours), then yes, you should use the safety pins for the bench on the squat rack.
But if there is someone around, ask for a spot. I have never been denied a spot, I imagine that's true for others too. Of course, it should really only be one set that you need the spot for. And I know I always watch the guy benching when there aren't many people in the gym, just to make sure they don't get pinned even when they don't ask for a spot. BTW, you should always do bench without collars, just in case you need to dump the weights. It happens to everyone sooner or later.
OHP I use the power rack or the squat rack. (and I certainly don't OHP 225lbs yet). If there is an adjustable rack that lets you start from up high, then I"ll use that, but there usually isn't and thus I use the squat rack. It's a real lift and no one is going to bitch about it. Now, if you were doing curls........................................