Can anyone explain what I NEED to have firsts and then how we go about discussing with the leasing office?

DO NOT work with this office.

We want to do some renovations and rent it asap as an office building.

You might just have an inexperienced loan officer (I've run into many of them) or a lending firm who has tighter policies. 

I went through 3 slow loan officers before I found the fast one I want to work with.

Especially w first few deals, the sweat-equity partner may only contribute 30% of value, so 30-70 is the arrangement, especially if it's a short-term JV...I think we hear the 50-50 talk from established investors who have built a long-term relationship w investor-partners.Yes, we could get into the minutiae of tracking the dollar-value the "worker" brings to the table over time, which I guess is the spirit of the "mini-mortgage" approach: Estimate the value of their sourced-deal if wholesaled; set an hourly wage for office-work/time spent renovating; charge a leasing fee for tenant placement and 10% of rent or whatever each month for PM moving forward... 

Listen to the all the books, buy the books and highlight the important sections, make a list of what you need/have (documents and office organization), and get on BiggerPockets.

I was talking to a loan officer at Bank of America, and he said he'd send me a fee sheet with his APR and closing costs etc., and that if I had any questions that he could answer them by phone. 

Sometimes, the loan officers don't now. 

You could contact the owner directly, go to the county assessor office website, you can call or email you the property owners information.