We budget for maintenance but don't set it aside, we pay it out of pocket when needed.

You should budget for your purchase price times 2.74%.

It's hard to gauge the reasonableness of these assumptions without more info on the property (address or at least zip code, age of the property, condition of the various components such as roof and foundation, among other things).I see you've budgeted $0 for repairs. 

But as Jeff said, since you won't have someone watching over you and you will have essentially a $100k checkbook its real important to set your budget upfront and stick with it vs just spending as you need $s. 

Budget price for a property: $200k maxCAP Rate: essentially my mom wants around 6-8%+ return.Ultimate Goal: to have cashflow $40k+/yr within the next 15 years.We also are not interested in the buy and flip strategy as my mom wants passive income through renting out.

I have been doing research and see that either a designer charges based on an hourly rate or a % of the over all budget.

I recently bought a house to flip, and it turns out it will cost much more to renovate than I'd budgeted.

You may not know how to handle: tenant relations, maintenance requests, contractors, turnover, lease admin, property managers, "professional" tenants, neighbors, capital expenditures, municipal codes, federal laws, evictions, lawyers, budgets, taxes, etc. and how each one can affect the profits (or eliminate them.)

Are separate meters included in your renovation budget?  

I have already asked my agent to ask the management of the building about the cracks and plan/budget to fix them.