Sarah,
I feel for you! I only have one so this type of behaviour bothers me too.
Honestly I don't know how to deal with it as my DD has a lot more energy to do naughty things than I have to deal with it! Maybe pick your battles. The things that really drive you nuts be consistant about and correct while letting other things go. Personally I would be more upset about the lolly than the couch cushions. If you said no, it should always mean no. Its awfully young to start thinking you're going to override mum's authority when you want.
As my daughter gets into her terrible twos, I am more and more shocked at what a little monkey she can be. Some days it never ends!! And then other days I get the million dollar hug that makes me ignore everything.
Erika
xxx