I don't want to be renewed automatically unless it's agreed upon the new lease.Today was the last day I stated for them to provide me with their decision and they haven't responded at all, I will send them a letter tomorrow morning saying that I expect them to leave by the end of the month and I refuse the renewal.

You would draft up a letter of explanation to go with the paperwork submitted to the UW. 

Personal hand written letter or not?

What has worked better for me (I have never done the email "farming" you talk about), is going on the county GIS for whatever county you are targeting, print out a list (or generate a spreadsheet) of the properties in that neighborhood/area, and mail them a letter.  

It’s more efficient to spread your cash out, but to some people they don’t like carrying all of that debt where paying for cash would be more preferable.

I have recently taken the approach of sending letters to owners of multifamily properties to see if they would be interested in selling.

I’m not counting any carrying costs since I’m living here. 

It's not only based on the different filters as you mentioned @Chris Forza, but also the type (and amount) of coverage you prefer to carry on the property.My best suggestion would be to reach out to an independent insurance broker who specializes in working with investors to learn what type of coverage you want on your portfolio and to obtain quotes from there.Best of luck!

In the offer contract letter for the second unit, our real estate agent changed from LLC's name to our own name.

For example, properties that are older and have fewer credit-worthy tenants may carry more risk, and as a result have a lower price, resulting in a higher cap rate.