Im planning on living upstairs which has a big finished attic and renting downstairs which has basement (huge) access.Im thinking of building a wall separating the basement (one side w only access to laundry machines) & one (just accessible to the downstairs unit.

It took me about 6 months to build this operation from scratch, because I had to make adjustments on the criteria I wanted apply in each of the verticals (I ended up with 9 channels), figure out how to get this info in the first place, then put in procedures to automate this process somehow (I started off with hiring VAs overseas, which in itself is a learning process, and now with the help of my IT friend who has partnered up with me, is in the process of automating the data extraction process using AI/machine learning). 

Over the past 3 months I’ve been a machine, listening to podcast episodes everyday, scouring the forums for posts to learn from, reading every guide I can get my hands on, and I’ve got several books in the mail that I can’t wait to read (Long Distance Real Estate Investing by David Greene & The Book on Estimating Rehad Costs by J Scott). 

Plumbing from the "old" washing machine hook-up could become shower stall (tub is not an option).

Even so, assuming an additional $5k in expenses, you would still be creating $10k AND have a cash flowing money making machine. 

I'm assuming this spike is from the washing machine usage?

That doesn't stop someone from jumping through all the hoops to get a showing and then spring the "oh I just saw you don't allow pets, I have an 8 lb [piss and poop machine] that is very well behaved, do make exceptions?"

The Master account being the one that controls the hallway and basement lights, laundry machines, boiler, etc.

Left messages on their machine.

I have a 12 unit building in a small town filled with great tenants who are older and never entered the 21 st century, They deposit rent checks in a lock box in the laundry room and once a month my wife empties the box and drains a huge pile of quarters out of the coin laundry machines.