Just because somebody says they do things a certain way all the time does not mean that is the proper way to do it ...

My questions is; are my only options to either wait for the lease to end and notify the tenant with proper notice that he can not renew or will I just have to give cash for keys a shot and hope for the best?

(Still confused about why there would be a sheriff's sale, since you didn't say there was a tax lien on the property.)Finally, if real estate investing is something you are serious about, you are going to have to learn how to properly value a property or find a realtor you trust to do it for you. 

I wouldn't be that concerned because the title company will make sure the proper owner is selling.

Under the hierarchy of home liens in Texas, property tax liens are only superseded by certain properly filed federal and state liens.  

And use the proper kind of tape on the joints. 

To get the real facts and see if and how a deal can be properly structured fitting the owners situation?

I know that it all has to be processed, I'm just not exactly sure how to proceed properly.       

Also I would recommend that you do a proper inspection proper to tenants moving in and make sure you have it documented properly,  In the event you have to go to court to recover damages the judge will always ask you how know the condition of the property before the tenants moved in.  

Electric and gas usually are the easy ones to do properly.