@Nadia, All I can suggest is try it. and if you aren't thrilled, I'd be delighted to refund you.

When I do the square footage wall to wall, using the designer drawing measurements, I come up with 574 total.I'm trying to determine if my feelings are correct that this space is worth more as as self-contained rentable space that could either be used as a MIL suite, or man cave compared to simple square footage with all the components.Of course, the added bedroom, bathroom and laundry are key components...but I'm not so sure about the sink, fridge, and convection oven adding that much to it.Is there a known formula that I can apply to this scenario? 

Each room is different one looks like a cave, one like a beach cottage and so on just research what that particular demographic is into, You might have to update the place more often but if your getting 2500 a month on a place that might rent for say 700.00 a month is could be doable. 

I'd be more than delighted to help Ron achieve his investment goals. 

Recently I bought a house where the ceilings had a plaster finish that I can only describe as looking like lemon meringue pie or stalactites/stalagmites (I forget which is which, but the ones on the ceiling of a cave).

You caved in on rent and lease term and made an agreement with him.

if you are enjoying your dealings with agents, you are going to be absolutely delighted when you get to deal with tenants, inspectors, city officials, and contractors.  

We all have probably had a negotiation that tested the very core of your patience, but knew you couldn't cave in. 

It is just another "secret" system to easy money with little effort and evn a cave man can do it.Two words for that, Bull S%!

You can still be friendly and build a relationship with a seller by not caving or wavering.