My wife and I just bought our first duplex. The previous owner had a tenant in it already, and due to how their management company worded the lease, the selling of the property didn't terminate the lease and we now have to honor it. Definitely not ideal to buy with tenants, I know, but due to the cash flow that the property will give us when it's fully rented, and it's location, we couldn't pass up on it. 

We're raising a family, and I definitely don't want a tenant that smokes, let alone that smoke next to my family to such a degree it can be smelled all throughout our half of the duplex. Even more so if it's Marijuana. I have three questions, and any advice or input would be greatly appreciated, thanks!

(1): There is a clause in our lease that says that if the tenant is in possession of a "controlled substance", they can be given a 1 day notice to quit. According to Michigan law, Marijuana (medical or otherwise), is considered a "schedule 2" controlled substance. Michigan law also says that we can't keep tenants from possessing 2.5 ounces of marijuana and under. 

So, my question is: would them signing a lease, agreeing that, if they possess a controlled substance they can be given a 1 day notice to quit trump the state law because of them signing in agreement?

(2): There is a clause in their lease as follows: 

"Rules & Regulations. Any rules and regulations published by Landlord become part of this Agreement. Tenant agrees to abide by all rules and regulations that may be published by Landlord."

Does this mean that we are free to draft up and add an addendum to their lease regarding a ban on smoking if we so desire? Would they, because of this clause be forced to obey it?