Get the property legally changed to a fourplex.Here's my approach with similar properties: I buy or renovate property that could pass the zoning process should they need to be changed due to neighbours complaining about the property or city inspections.

I've also watched hours and hours of videos and to be honest all the information is very valuable but it seems like it applies less to your favorite neighbours.

Is the entire lot the 12x100 strip or is that like a panhandle portion with the rest of neighbour A's lot accessible through his own property? 

My house was built in the 50's so I can probably guarantee it's going to be the small one although the meter unit looks as modern as the ones anyone else has...We could tie into my neighbours sewer system (I'm joking but actually there must be sewer close to where it is as it would be between two houses not behind).

I have seen this before in Greece.

Neighbour lying about the property to buyer and them pulling out.

My neighbours sold their house 6 years ago, new ones have an unlicensed daycare... probably 20 times I’ve had my dogs in the backyard (they’re inside dogs mainly) and had to go get them because kids are sticking their fingers through the fence etc.

The main reason for wanting to make it a 1 bed is because there is almost no natural light in the living space at the minute.The windows on the non-bedroom walls are so close to the neighbours property that they hardly let in any light at all.

Why should you give notice if you are working on the neighbouring property? 

Look around a bit in neighbouring areas though a cash flow of $150 a month, isn't bad.