Honestly, while it is easier said than done, being calm and rational is the best response. She is acting like a child so you need to act like an adult. If she gets aggravated, you stay calm. If she shouts, you ask why she is shouting, if she throws stuff, ask why she is being violent? She charged into your room without knocking? Point out it is your space and she has no right to invade it, then take the conversation outside of your room - that isn't her space.
Likewise, if she wants to shout at you about arrangements with your parents, inform her it is none of her business - that is an arrangement between you and your parents.
It sounds like you do things to help her out, I'm not quite sure why? Next time she asks for help, state you're not willing to help her because she is rude and abusive towards you and you see no reason to be a decent brother to her and help her out if she isn't going to be a decent sister to you and show you some respect.
I'd also invest in a decent doorstop if your parents don't want you to have a lock. It'll at least give you a few seconds to breath and answer the door before she charges in.
It all sounds pretty crappy to be honest, but the best thing you can do is try to rise above it. Filming some of it would also be useful. If you can consistently show you've behaved mature and rationally, then this will add weight to your claims. Likewise if she admits to taking drugs or anything on camera, you've got solid evidence to present to your parents.