I have filed multiple claims across several properties and some have more than one claim (all within 1-2 years) and I have not had any rate adjustments.

I built a crazy spreadsheet to calculate the late fee and we manually calculate it on all tenants currently each month. 

You could adjust their rent as you transition them over at lease renewal letting them know that $50 of their rent covers the heating cost, so they pay $50 less per month and now pay for heating directly.

What adjustments should I make when sizing up a commercial property?

I’m very near closing, just wondering what sort of documents are important to request of the seller (I.e. maintenance contracts, manuals, warranties etc.)

In that case you would want a fixed rate not a adjustable rate like a HELOC.

If MFH, it's closer to 500'ish but many specific variables rapidly adjust that such as use of on-site PM assistant's, caretakers etc..

Have prices dropped significantly (back to 2018-2019 levels, even after adjusting for inflation)?

UPDATE: I had a good conversation with the ALE relocation specialist yesterday, and she's submitting the pricing info I requested to the insurance adjuster.

I'm not a big fan of adjustable rate loans.