However I'm in my current lease until May and I like my current living situation with my two roommates.

Send each tenant a letter letting them know you need them to sign a new lease that will contain a rent increase schedule.  

I have a lease addendum that are house rules, specific to the property.

If a rental/lease contract is a legally binding document...enforced by collecting rent...or enforced by an eviction process if rent is not paid....then can there not be a document (legally binding) for a tenant to sign that would relinquish their rights as a squatter or due process of eviction...

We ask simply questions, like were they late, did they have lease violations, outstanding debt and would you lease to the tenant again.

Get a 7-10 inspection period to check everything out on the inside of the units but also make sure to get the leases to review during your inspection period. 

Review their lease agreement and addenda.

I know its expensive but you will be well protected :)Or you save a lot of money and be better protected by doing this consistently and well:-carry appropriate types and amounts of insurance-sign contracts with indemnification provisions- obtain all necessary licenses and permits to operate your business-ensure all vendors/contractors are licensed and insured and list you as additional insured-sign well drafted and fair leases and be a responsive landlord -be an active owner or hire an active PM  who avoids or at worse timely eliminates premises liability exposure The strategies you often read about are sold by alarmist asset protection companies who fail to disclose how impractical they are.

And if you time it just right when your tenant lease comes due, or have a tenant that just needs the extra space, then it’s a win win since you dont have to have any vacancy. 

At a bare minimum, I would require a written lease agreement and a standard security deposit equal to an entire month of rent.