Even with a concrete lease, it will not necessarily protect you, tenant act still is strongly for the tenants.....you must jump through their hoops and it can still take over 6 months to legally evict a problem tenant, so chosing carefully is important, its much harder to live with tenants then those who just have a rental property. Again though this is more for house then roomers, different rules..
After seeing my mother go thru a tenant from hell. Work it in your lease that you have a way to kick them out with need be. My mom has it that she can kick them out when they've become a nusence and after the tenant taking her to arbutration 5 times(tenant loses), damaging the house, harrasing her with phone calls (live in the same house), she still doesnt have enough to warrant kicking her out according to the landlord and tenant board. Your lease is your safety net. Work it up and take it to a couple fellow landlords and see what they say about it.