Interest rate shouldn't be the biggest concern, qualification and then terms (amortization, balloon, ARM or fixed) and then interest rate to back into profitability is the way I look at it.

Biggest piece of advice is to make sure the numbers work BOTH as a house hack and pure rental.

The biggest problems we have are with wholesalers misrepresenting what they are doing.

There are other creative financing techniques (partners, owner financing, wrap arounds, etc), however, items 1 & 2 seem to be the biggest impasses that I see young investors running into when they are starting their careers - the third is the down payment, which you have - well played. 

How much time you need to gain appreciation depends on the asset, the sub market, and most importantly the investor choosing and managing the asset, and in the most extreme example your lifespan.Risk in real estate investing comes from two sources. the 1st and biggest contributor is investor error.

The biggest piece of advice I can give from this experience is don't try to do everything yourself.

Without some financial incentive what is the point in the land owner working with you, or the buyers, etc.?

1) Not investing - Not investing in this asset class is the ultimate, biggest mistake you will make with your finances.

Of all the people I've helped over the years the biggest question I've had for THEM is "Why didn't you get started?"

I have heard from several seminars, meet ups, mentors, etc. that one of the biggest mistakes new investors make is that they pay contractors money up front and end up getting ripped off (the contractor never does anything and just takes their money and runs).