First house which happens to be a duplex

[Jacob Buckles]

Just for a little back story...

I am young (24), I have never owned a home or any kind of property in my life and growing up my parents always rented. I was renting for a little bit at a duplex and not too long ago, the owners asked if I were interested in purchasing the house and threw a price out that I really couldn't say no to and took a pretty decent risk.. The second unit already has a renter and now I'm scrambling to figure out how to do this whole thing and not plunge myself into a hole I can't dig myself out of later. I sign the final paperwork in 2 days and I've been trying to get as much done as I can early, so I can actually enjoy home ownership for a little bit lol.

1.) I paid a law firm to write up a couple leases for the current tenant in the other unit and for my roommate as well. I can edit them freely, they should be up to date on local laws/regulations and I've read them several times over. Things I should keep an eye on that may bite me later on?

2.) The house being the age it is, may or may not have asbestos and/or lead paint. Tests were never done, it is just assumed that it does because of age. So, disclosure are currently in the lease for those two items. Should I leave those disclosures out of the leases since test were never done and there's no exposed insulation and/or peeling/chipping paint? Should I pay for the tests to be done so I can be absolutely sure? Should I just save money and the assumption that it's there be enough along with the disclosures previously mentioned?

3.) The tenant in the other unit lives alone, has lived there for 6 years, never missed a rent payment and hasn't cause single bit of damage. Their area is in immaculate condition and I really want to keep them for as long as possible. What are some quality of life improvements I can do in that unit as maybe a little welcoming gift to show my appreciation and maybe get off on the right foot? I was thinking a dishwasher, since the unit currently doesn't have one and it would save on my water bill in the long run while making their daily life significantly easier or even possibly offering a discount on the rent for the next month as a thank you for the cooperation while tons of contractors, inspectors and appraisers came in and out of the unit this past month. 

4.) Like mentioned previously I have no idea what I'm doing in all aspects... I'm not getting rich off of this. In fact the rent just barely covers the mortgage. Utility cost and other costs associated with owning isn't anymore than what I was paying previously in rent and most of the time is less. So while I'm not any better off financially in a significant way, I suppose the money isn't going nowhere anymore. Not to mention I've pretty much drained the reserves I've saved over the past few years so I'm currently in a touch spot where one bad thing could ruin me until I can get my bank account back up to where it should be(gotta take risks in life I guess).  In todays day of age it seems everyone has a giant chip on their shoulders about landlord and think everyone of them is the devil, so what can I do to protect myself and how do you spot people who are going to take advantage of you when screening for new tenants once that time comes?