More demo work New vanity coming soonDemo workLeaking from 2nd floor bathroomMold found behind the tiles

I'd recommend you start with a small agreement, doing maybe demo and if things work well, moving on to framing or whatever next. 

Demo existing wires$35,000.Is this normal from electricians on such an extensive job?

good advice here. one thing to consider when a plumber is charging you $250/hr, you only want him to do plumbing. not demoing, trenching, jack hammering, re-installing tile, and other such stuff. keep shopping quotes. 

Demo to that point is pretty severe. 

Just closed on our first rental property last Friday, starting the demo today.

Because you have more then just the demo/rehab costs here, you also have a lot of added days on the turn where it will be un-rentable.If your workers are good you might be able to turn that unit in 5 days (without the opening up), including kitchen counter upgrades.Also, will removing walls trigger any required upgrade to the electrical system to bring it up to current code?

It can be very expensive and often cheaper to demo and start over. 

He just finished demo-ing the old building and told me that our property encroaches on his (according to his survey) by 4 inches- the 4 inches are all sidewalk but would make the walkway on the side of our building narrow if taken away.

As to getting accurate labor costs, if you can form a relationship with a contractor, you can certainly pay him for his time to do one sample bid for labor on all the items you should need (window install labor, trims per LF cost, hang/install interior/exterior door, demo a bathroom, demo a kitchen, demo flooring, tile install floors and walls per SF, etc.)