Inherited house turned rental

My sister and I inherited my parents' paid-off house in Wilmington, NC, with no appraisal at time of death in 2017.  Sister was executor and maintains that the estate owned the home until it left probate in June 2019, from which time we co-owned it.  I worked on the house February and March 2020, and purchased her share of the home in March 2020 with a mortgage (my second -- I already have a primary mortgage) to acquire it as investment property (not primary residence).  My sister moved out of the home at that time (she had been living there rent-free).  Renters moved in the end of May 2020.  I have already paid for three appraisals on the house (one ordered by my sister as executor in February 2019, one in fall 2019 to qualify for mortgage, and a third in February to re-certify the results before closing). Do I have to pay for another, retroactive appraisal to get Fair Market Value on date of death? Or can I use the alternate valuation date that my sister as executor used? Do I list the mortgage interest and points as a second mortgage under deductions & credits, or under rental expenses? Also, do I need to issue 1099-NEC's for painting to get house ready for rent, etc.?  House would have been ready to rent in March if the pandemic had not hit, as I had to return home due to lockdowns and could not work on the house again until May. I probably lost rental income due to that, and had to pay mortgage payments out-of-pocket during that time.  Is there a tax break for that lost income potential, or do I have to list every day in 2020 until the renters moved in as personal-use days? Thank you!!!