Maybe change the meaning of the fourth "R" to "Replenish" since you are getting your money ready for your next acquisition.

Knowledge, you want a custodian that knows what they are doing and can help explain the rules and prohibited transactions to you

A quick rule of thumb is using the 50% rule to calculate cap rate.

May I pay down the replacement property further- just want to be sure that I follow the 1031 rules without a boot?

The house was built in 1960, so when it was put it, there were probably not rules against it. 

I wasn't able to find anything on this though.Does anyone know what is required, or have a general rule? 

Obviously the property is very solid and LTV is 75-80%, but as a rule, it does not hold forever...

I have heard of the three boxes of saving, spending, and giving, but I have never thought of adding that fourth box of investing.

But ya I aimed for 3 bed 1-2 baths, cuz I can always live in one of them, or the basement if it is good enough to clean and actually stay. and rent out the rooms. check out prices for one room in your area, or near by apartment complexes and base your numbers / deposits and rules off of them

@Ovais Zuberi, so it looks like you'd be into it for about the "1% Rule" mark.