Kudos to you, searching for help!

It sounds like Oscar is running the show, and you (and wife) are dancing to his tune, and reacting TO him. You need to turn things around, so YOU determine what is happening, YOU are acting, and he is reacting.

So you see him doing something you don't want him to do. No scolding, hitting, spraying. You've tried that, it isn't working. Instead, get something he WANTS and play with it. Distract and redirect. Keep a few toys hidden in each room just for this reason, so you have someething close to grab. Put it back after.

You need to spend "quality" time with him. Keep a few toys in a can w/ catnip, just for this purpose. These toys come out to play with YOU present. These are SPECIAL. When you leave, you take "your" toys with you.

Plants and cats, tough one, easiest solution is NO PLANTS. But there is a REASON he eats them. He is not getting enough chlorophyll in his food. I use Barley Cat. This satisfies their need. Here is a link so you can see what it is; you can probably find it less money if you search. It is a powder, you shake a little on their food.
http://www.vitacost.com/Green-Foods-Barley-Cat

Child safety locks on the cupboards will solve the food raids.

He sounds like a child doing anything, ANYTHING! for attention. Like the children on Sound of Music who div all the nannies away, the only way to get their Father's attention.

You didn't mention if Oscar was like this before moving in with you in the apartment. H chewed a hole in YOUR shirt. Does he eat wife's clothes too? Or is he just dying for YOUR attention?