Needless to say, I'm beyond excited to learn more, figure out the process, gain confidence, find a core 4, learn more, study more, and I feel that the wheels are finally on track and I have direction and purpose.

With the very limited information you provided and the way you presented it, you made it sounds like you were just jumping in and buying land without actually doing any feasibility studies. 

Cost segregation can find more deductible items in your property, but full cost seg study on a $390k house is probably not worth it.

If it's truly valued at $400k, you could pull out up to $300k with no tax implications whatsoever (you'd be taking on debt, not incurring a capital gain).With regards to depreciation, engage a great CPA who understand and specializes in real estate investing, and ask them if it's possible to use a cost segregation study to take accelerated depreciation.

Is there a single comprehensive book/resource which could be a good bible to learn from/study?

They will send you paperwork to fill out to prove the ownership and enter in your direct deposit information for payment.

How will you prove their identity?

I just recently began studying wholesaling.

How long should I study before I begin my journey to buy and renting my firs mobile home, without becoming a person that looks into it so much and never take action.

I had thought that 2020 would prove this to people.