Initially tenants may not notice, but I do feel that it is more difficult to increase rates once they are in the unit. 

Here question to me below:BANKER RESPONSE: Just a quick note to say that I’ve reviewed your initial proposal and will be running some global cash flow numbers to see how they look.

I am looking at purchasing at trustee sale initiated by a junior lien.

If the norm for a duplex in the area is that the tenant does lawn care I would stick with that model, you could add an addendum to your lease that says XX dollars is charged if there are any citations against the property.  

This number is going to be different across every market, asset type, and lender, but it's something that each lender should provide in their initial preliminary quote, and in most cases is negotiable.I'll usually ballpark reserves at ~$250/unit for stabilized multifamily. 

The only problem was, that renewing cost was double and depending on your plan, they also charged me $100 for every service call.

In general we like to take a measured approach that breaks up the DD into 4 areas: financials, initial walkthrough, compliance, and paid inspections/services. 

Ideally you can extract your initial purchase costs and the cost of the rehab but in full disclosure I have never been able to get all of my investment money out via this process (but I have gotten out almost all of my investment money).I am a big proponent of the steps I outlined. 

Do we charge a little less if she signs a 18 month or 2 year lease?

What Ido is charge a fee equal to the value of one months rent.