I think the first thing you need to focus on is environmental prevention. Make it physically impossible for him to go in and disturb his sister, so:
-move her cot into a different room/area that he cannot access - use baby gates and/or locks on the door so she can have quiet time to settle, this isn't the same as locking him away from you, but ensuring she can settle. ideally your husband will play with him while you put her to bed, or vice versa
-physically separate them at mealtimes so he cannot hurt her. to be honest i don't quite understand why you are so resistant to the high chair as it will probably help both of them, but a pp's suggestion of sitting round the blanket was good. sit in between them (keep him on reins if necessary to stop him getting at her), focus on rewarding both for sitting and eating quietly and calmly.
-child proof your house better so that he can't damage things you care about, any time out area needs to be devoid of ability to engage in distraction/attention seeking behaviour. if you continue to use the stairs just ignore him if he pulls the paper off for the time being, he won't do it if it isn't rewarding in some way to him.
-lock the front door so he can't run out, and use reins when you're outside so he can't run off. he earns his freedom by showing he doesn't need them. any misbehaviour, put the reins back on, explain mummy needs to keep you safe now so this is why we need reins.
-use playpens to separate him and sister with you in between, so you can interact with both, but they can't hurt each other.
You need to use his environment to help him make the right choices and set the right boundaries. wouldn't it be easier if instead of constantly having to grab him and prevent naughty things happening, he didn't have the option of naughty behaviour?
buy robust toys he can't easily break. if he breaks them, don't punish, just say whoops i guess toy is broken now. make it easier for him to make the right choices, where possible set his environment up so he only really has the option of doing things either that you want, or that you don't really mind (if he breaks his toys, they are his, so it doesn't really matter...he will learn himself that it's probably better to have unbroken toys)
i promise it will be much easier for you!