Suggestion #1 isn't really needed. There was a debate about this, and it's really not all that necessary. It could be done, but it's not that important.
Suggestion #2: Could you explain a little bit better? Controls could be improved, such as creating custom keys and having keybinding options, so that makes sense.
Suggestion #3: This makes more sense for something like one of those limited programs, but PB isn't one of those programs. If we did this, it'd make it easier, but also would be like the old limiting PB systems. There's virtually no purpose in this.
Suggestion #4: You actually can do this, but it's a new feature and is yet to be improved. It requires commands (commands may seem intimidating, but they're really easy to learn.) It's mostly just using things like custom sprites that make it work.