Rental real estate trades or businesses expenses belong on Schedule E and are passive unless the taxpayer or spouse is an RE pro (as defined under IRC Sec 469 and related regs) and material participation (as defined in the 469 regs) is involved."

Are those A & B class areas defined at all?

many investors use median household income to define class rather than an arbitrary definition

Often fees paid up front are defined as security deposits or application fees which both can have limits. 

Only you and your CPA can define those parameters and decide best course of action.Based on the information I glean from you, I would do the 2019 acquisitions and go from there.Like @Michael Plaks said, if you end up with net rental losses, adding to them the extra CSS depreciation is not going to help you that year (!)

define your goals....that how to start

Start by clearly defining and objective and then researching the markets that will best fit that objective.

In the original legislation 1400Z0-2 it defines an opportunity zone fund as: The term "qualified opportunity fund" means any investment vehicle which is organized as acorporation or a partnership for the purpose of investing in qualified opportunity zone propertyThe later regulations clarified that an LLC would count as a partnership when setting up a an OZ fund, but under the IRS rules for an LLC to qualify as a partnership it has to be a multi-member LLC.

IMO, the fact that, the only debt you have is mortgage and student loans is a great thing.Sounds like you have the "more time than money" scenario.I'd challenge you to get 3 meetings per week with real estate professionals (agents, contractors, flippers, brokers) share your story/plans and you'll more clearly define your next steps.Also, i may be wrong, but 20% down would only be required if you didn't plan to live in the property.  

While wholesaling is legal in most states, several states have passed laws defining wholesaling as brokering and are requiring a real estate license to wholesale property.