Eventually I'd like to get new tenents, one that don't have a large dog (safty issues) and the other is a hoarder(currently no active lease if I do have them sign a lease it will be month to month). 

Its all about running your numbers.It sounds like your long-term goal is to have a large portfolio of rentals.Therefore, if the ARV of a property will generate a strong profit for you and the cash flow isn't great (or you can use your profits to purchase another property with better cash flow), sell it.If a property generates great cash flow for you, keep it.

Click2mail is extremely easy to use and great for large amounts (250+) of mail. i just wanted to make this round a little more personal so a lot of manual labor will have to be done.

However, on a scale of 1 - 10.  

I rented it for 2,750 per month a large house plus guest house and was able to dived a 3rd unit and still had lots of room for me and my family.

The sum is too large to come up with upfront, so I'm trying to double check if this is an absolute requirement.Is it?

That's why most experienced flippers use projected profit and expense numbers, not percentages.The 70% rule is nothing more than a quick and dirty way of screening potential deals, and was derived from an average over a large number of flips with a large variance of price points. 

First off - I'm total noob so trying to learn a lot.I'm looking to buy a condo or townhouse which I plan on keeping long term as a rental property.From looking at Zillow I noticed that there are some large-ish neighborhoods where there are few to no properties for rent, and others where there are several properties for rent in a condensed area.All things being equal, is it better to avoid areas where there's a high concentration of rental properties?

While working in commercial lending, I saw several investors holding large multifamily/commercial buildings in LLCs.

Google "bifold door ideas" for inspiration.I guessing you have plain slab interior doors in the rest of the house, so I'd recommend a simple, clean design to complement... like louvered, or a multi-paneled shaker style, or with large single frosted glass panes (they'll glow when the light is on in the laundry).