I have some telling me that I can do minor repairs on the property and use a credit card to purchase materials (HVAC Filters, caulk or even paint) and my IRA can pay the credit card directly (keeping it at arm's reach).I also see where this interpretation of services versus repairs could be considered a "Grey" area and I am just looking for something that turns it at least a little darker.

Supply & DemandUnlike financial markets, real estate prices and rents are driven by supply and demand.

Any advise on materials?

Additionally, I’m unclear on how their ARV analysis is conducted since most properties can be found on Redfin or Zillow — does it involve an in-person visit, or is it purely data-driven using comps and suggested repairs?

In Georgia my average materials cost on a new roof is $2,850.

Also in 2022, Ford increased the cost of the Lightning by upwards of $8.5K due to (ahem) "more expensive materials".https://www.caranddriver.com/news/a40848342/ford-f-150-light...

Only thing I'm not sure of is the old countertop material, but it does look look in the photo. 

Not necessarily land, as it is very costly to build there as all materials except for some concrete products have to be shipped in.

The local hardware stores and big box stores sell materials, they hire local workers.

He networked with investors and offered to pick up and deliver materials, then he cleaned and secured the worksites every night.