My plan is go in put in professional management, repair, raise rents.  

Setting aside 5% for repairs, left me with $2400, or $200/mo. 

My plan is go in put in professional management, repair, raise rents.

I guess that's why we include repair costs in our monthly expenses

At the point of the repair for damages reaching the $650 security deposit limit, would it have been legal to give the tenant a 30 day notice to leave the property due to excessive damages? 

If your tenant lives hand to month like many others, I would personally recommend against this because the tenant will be disincentivized from doing repairs or even informing you of major repairs even when absolutely necessary. 

If it fails and you can't repair it - you might also be responsible for clean up.

Sellers—agreed to make NO repairs after inspection, but agreed to pay $1,000 at closing to buyers for repairs to be made (on a $119,000 house that had just been fully renovated). 

My biggest struggle right now is trying to figure out how to properly estimate repair costs, so any suggestions there are appreciated.I have been thinking about taking the leap for years, and have finally set myself up to be in a position to do so.Can't wait to see where this goes. 

That's really going to be a waste of your time.What I do is ask for 6 months of Bank Statements where the rent was paid so I can see if the rent was paid on time.Basically, if they can't give me proof they paid their rent on time, I go on to the next candidate.If you even get a few checks, you can see who got paid if you really want to call the current landlord.However, doing the employment, tenant credit, eviction and background checks along with having them providing Bank Statements corroborates their story of being good, prompt paying tenants.BTW, I'm a NYC Broker/Landlord.... it is REALLY important I don't put in a bad tenant.