Thanks for the feedback!
1. That's a good idea. I'm wondering how to implement it, since pins that stand back upright can become dangerous again. Maybe it'll be a simple visual cue like a stopped animation (I'll have a walking animation for the pins) or a different looking sprite.
2. This shows I have to make the frame/ball number system clear, as the pins spawn after you roll and pick up two balls, like in a bowling frame.
3. I agree! This one is something I'm trying to improve. Right now it has a semi-functional workaround, but my current plan is to make the actual area look more like a bowling alley and have the spawn area (the end of a lane) inaccessible so that pins don't collide upon spawning.