In the Northeast, the amount of money you can make is completely normalized by high lifestyle costs.

Oh and I'm not necessarily afraid he will bail on me at closing I was just making sure that double closing would be the route to go since the assignment fee is higher than normal deals.

He has and will drive vehicles until the wheels fall off,  he has a decent boat, and doesn't live a flash lifestyle, doesn't care to, however, he does own 2 timeshare properties, that him and his wife go to every year for vacation.

When I do get one, it will need to generate some cash on normal months (e.g., after property management fees, but not taking into account maintenance). 

My guess is that the tenants are correct, that is a normal amount of notice.

That would leave me $2560/month to live on, which is enough for my modest lifestyle indefinitely. 40+ years I hope.At this point, I could consider myself "retired", in the sense that my only job would be managing the managers of my proprieties.So, am I dreaming?

Personally, I'd ask him how much it increased and if it is a reasonable amount I would verify his normal bill and pay the difference to get the situation resolved and hopefully build a quality relationship in case it is ever needed.Just my two cents.

A few percent might be normal due to building crashing years back but high single digits to double digits shows a deeper problem on the micro level where the property is located.  

No you do not have to visit it but if you want to maximize the chances that the listing agent to take you serious and present the offer properly you normally have to visit. 

Then again, the above assumes you're representing the buyer client as "their," agent and trying to make a profit on their home, AKA making an extra commission that is off the settlement statement, apart from your normal commission.