Also, all my units are master keyed already, and I don't want to mess with that system :)  Agree on the battery life however - I put them on my office 4 year ago, and just changed the battery a few months back for the first time!  

He and his wife (who has her masters) graduated and got real jobs in 2014, bought a house and had a baby. 

Structure a Master lease with the owner making you a Tenant.

A few things I noticed (1) you didn't include gas in your expenses (2) management expense at 6% seems low - I've used companies <10% before and I paid for it (3) billing back utilities via RUBS (Ratio Utility Billing System) is a legal, extremely economical way to bill tenants their fair share on a master metered property, however, make sure your state statues support it and is fairly commonplace with your competition. 

The house was there on the market for close to 300 days.We got the inspection report and it showed that there is a plumbing issue (leak from the master bathroom, see attached pic), which looks like a red flag to me but my realtor (might be biased to closing this deal) has asssured that this is not a major issue and can be fixed.I have requested the seller to fix the leak plus bunch of other minor stuff in the request for repairs.

One of my properties has a master lease so the entire building is rented day one and I start getting the entire rent check which makes for a very quick stabilization period. 

I am a newer investors in Tacoma, Wa and i am interested in approaching motivated sellers with a Master Lease Option but I have concerns about them backing out/not selling.I would want an attorney but even if all paperwork is order is there any gaurantee that I can buy it if I choose?

Pick what resonates best with your long-term strategy, or pick a few since you're only 20 and have plenty of time on your side and master as many as possible. 

We have lesser finishes, but if we refaced the cabinets (since it's cheaper than replacing, and more durable than painting) and swapped the countertops (laminate) we could likely demand more rent, especially since it's a top-floor unit with vaulted ceilings, a huge master, and no shared walls. 

Become an apprentice to the craft you want to master.