are you going to be able to buy deals at a deep enough discount for them to work as a BRRRR? 

Helocs are driven by the Prime Rate which is 3% above the Fed Discount Rate.

Then we see if the current tenant later decides to extend or we list the limited open period, often at a slightly discounted rate. 

Pro - You can get significant discounts buying cash, to build in more equity day 1

If you purchase at a discount, then you'll be capped by your purchase price, not necessarily the as-is value of the property.

My contractor is a skilled tradesman who won't beg me for work or give me discounts even though I told him I am an investor cry cry cry...

Then you take that list and see if there is crossover with some of the areas you are interested in and start there because you have a competitive advantage there (boots on the ground or knowledge).One last thing, don't discount your own enjoyment.

Particularly power related tools since those are usually discounted for Black Friday. 

If you are not coming in cash and you plan to hold for five or more years, its the best time to pick up a property at a steep discount and make it work until the cycle turns again.  

Say I have a first position performing note, what is a typical discount I should expect to give when selling?