I agree with minimising the use of no and don't and try to use other ways to talk to DS for instance if he is going for the stereo I will say to him to "away from the stereo and come play with this or cuddle me" or whatever...

A suggestion for when you are feeding, can you set up a couple of little boxes that have some stickers and a book and some little snacks like my DS loves, loves sultanas so a little pack of them would be perfect. Then you could give it to her while you are feeding to keep her a little distracted while you are feeding...

I think they can learn not to touch but I don't think it is always a wilful defiance, I think that they are getting attention from it as well as testing of your reactions and boundaries and they just can't help themselves... I also agree that if you leave something within reach then there is always a chance that it is going to get broken so move it. Just my opinion and I have a dp that doesn't always agree