Let them tell you whats needed and work with them through the process, establishing that you respect their authority on the matter and are trying to work with them can go a long way in making your life easier.For reference, a simplified lift of drawings required for a typical house permit in my area are:- a site plan, - floor plans for every level calling out life safety elements, dimensions, etc- building and wall sections describing the construction of all the building components as well as their r values - building elevations - Architectural details - Structural drawings and details- Structural Calculations  Hope that helps, feel free to reach out with any other specific questions you might have.

(windows have to have a certain opening dimension and so forth)

ie, outside dimensions, inside dimensions?

Both baths are the same dimensions and right over each other.

Also note that depending on your lot dimensions you may have more restrictions than the neighbors you reference.

It'll also show footprint dimensions for non-interior space like garages, carports, sheds, etc. and label what they are. 

We need to get all dimensions and figure out what's load bearing and what isn't, but that would be huge value if we could do it. 

There are some dimension and square footage minimums, but those can be overlooked by a willing occupant. 

Doesn't include basements or unfinished spaces like attics.The lot size is related to the property dimensions like a 50 x 100 foot lot.You could expand, but it depends on the lot dimensions. 

That being said, those are standard sized lots which are 45X95 in dimension.