Having been in the lending space for a while now,  Interest income is not passive - its considered/taxed as ordinary income- just like interest you receive from your bank and savings account.Regarding profit and expenses from a flip, "that depends" on many factors but again if its short term capital gains, its not tax friendly.As always consult with your tax advisor / CPA. 

And a second question, How much interest should I pay to the people lending me some money?

It just starting to feel like its impossible to get less than 100k in lending no matter how secure the deal is

I spoke to my lender and they advised me to wait a year or 2 before applying for another mortgage since I just purchased my primary residence.I was thinking of looking into a Hard Money loan instead of traditional lending in order to start this project, in hopes of selling the property once fixed and paying off the loan.

I suggest you look into commercial lending, to learn about it before you require it, and start looking for people in the lending space who can assist you as you move forward and with whom you can develop relationships.You now have mad skills and experience doing the whole demo and rebuild, and if you can repeat a few times, your one deal enables you to add a couple others.  

This is exactly who most syndicators target.Then you get into family offices and institutional money, who can write $5mm+ checks.  

We specialize in the bank statement lending space.

Both can be powerful tools for investors, especially when you’re looking to maximize cash flow and returns.Since most lenders have a minimum loan requirement of $75K, you might want to explore hard money lenders.These lenders specialize in funding investment properties, even for amounts below traditional lending thresholds.

YES  How was your experience with the lending process on this?

I found a DSCR lender that will probably lend 50% LTV on it so I’m going to try to move forward with that.