If you let him stay you really do need a rental agreement, so that if you have to evict him you have the agreement. 

Listings are staying on the market longer than they used to.

I posted something like last year on this, and I was surprised how much people were not aware of or were not concerned with this fact.

One possible pro for the office building is that businesses may stay longer than residents.

I would advise you to stay out of your parents financial life.You should also be moving out of your parents home then if they choose they can rent out your space . 

Just trying to staying liquid for the upcoming clearance sale when the economy tanks.

I also want a return on my investment for my bachelor's degree in construction management, and staying in that field justifies that. 

No evictions on tenants placed by him in 8 properties over 5 years.Downsides: turns are more expensive than Id like although he has been able to increase the average tenant stays and that has helped. 

For those who have 5+ flip projects going on at one time how do you track all of your expenses and stay organized? 

There is some great advice from Josh and Brandon with quite a few newbies and experienced investors staying how to best get started and what books you should read.