Start with BiggerPockets Ultimate Beginners Guide (free).

Ultimately, the keys aren't THAT important since, as @Russell Brazil correctly pointed out, you really should have the locks rekeyed anyway.  

@Martin Guerrero although you can (and often should) bring a GC with you (esp. if you plan to do a rehab), if you want to become a successful RE investor, you should make it a goal to become proficient at evaluating properties (meaning: evaluating problems with the property, likely costs to remediate problems, potential value add opportunities & associated costs, etc.).Ultimately, you want to become almost as good (or maybe even better) at evaluating properties as a GC and inspector.   ...Once you get to that level, you become an invaluable piece of your due diligence process, and your due diligence process involves three experienced pros (you, your GC, AND your inspector--which is much better than just a GC and inspector).  ...at that point, your due diligence process is multi-faceted and very robust (which is critical to success in RE investing)....you can make your due diligence process even more robust by adding an agent who is highly experienced in property rehabs, RE investing, and who understands how to evaluate properties.Good luck out there!

Start with BiggerPockets Ultimate Beginners Guide (free).

Best advice I can offer is to wait it out, or go direct to seller, once the property hits the MLS you are competing with everybody and ultimately paying commission adding upwards of 6%.

Your annual budget and reserve funding documents can shed light on that, and you absolutely need to understand them.Owner's are ultimately responsible to pay fines, and typically charge them back to the tenant directly, or if they are using a Rental manager to oversee their unit, the PM would do so.

Ultimately, you want to get to a place where you buy the property (all cash, hard money, construction loan) and then finance yourself out to get appraised value. 

Ok, now that you have taken your initial step, below are some quick links to get engaged.Since you mentioned an interest in buy and hold, I added a couple links below on this niche for your review, while waiting for local connections and feedback on the Kansas City area. http://www.biggerpockets.com/startherehttp://www.biggerpockets.com/meetSetting up Keyword AlertsHow to Use @Mentions on BiggerPocketshttps://www.biggerpockets.com/ruleshttps://www.biggerpockets.com/inviteshttps://www.biggerpockets.com/forums/categorieshttps://www.udemy.com/biggerpockets-real-estate-investing-course/ (video with 64 lectures and approx 6hrs of material)https://www.biggerpockets.com/real-estate-investing (Ultimate beginner's guide to REI)REI can be very daunting, but, before you go searching for that 1st buy, please take a few minutes to bone up on the tips in link below.https://www.biggerpockets.com/renewsblog/2014/12/19/real-estate-investing-success-smart-tips/REI books suggested by BPershttps://www.biggerpockets.com/renewsblog/2015/11/13/7-real-estate-books-beginner-investors/ (7 absolute must read books for beginner REI)http://www.biggerpockets.com/renewsblog/2013/04/14/best-real-estate-books/?

Aloha,If the mother is already staying there, past the stated "guest" period per your Rental Agreement, then you have a couple options. 1) send a notice of violation to the daughter and follow through with your violation policy...ultimately eviction for other than rent owed, hopefully.

Ultimately you are going to pay the price at resale, or when trying to rent the units for doing the cheaper fix.