Also, is there a better or more comprehensive site out there for doing checks?

By far the best or most comprehensive coverage at the lowest cost is a commercial lines policy issued by Erie Insurance ( Erie is a superior policy to Zurich, USLI, American Modern Insurance Group,  Llyod's of London, and all of the captive insurance policies).  

-- e.g. off-market campaigns, short-term rental followed by comprehensive remodel and resale, owner-financing, etc. -- What strategies give you or your offer the edge?

Going to market in a few days and need a more accurate and comprehensive guide that's not woefully unrepresentative or a big advertisement.

Here is a very comprehensive beginners article I wrote on the subject recently:https://www.biggerpockets.com/renewsblog/cost-segregation-why-give-your-money-to-the-irs-when-they-let-you-keep-it/

Here's a link to a file that is hosted here on BP that seems to be comprehensive enough: Of course, consult your attorney to make sure it's A-OK in your state. 

The Investment is calculated in the D to E columns, Rows 1 to 8.Because I used a Mortgage of $119k and only Invested $28k including Closing Costs, I am able to generate extremely high ROIs.If this property was kept by me (It's not, this is Marshall's property now and I'm just using it as a demo for this example), and I sold it today, the Sales Proceeds would be $837k as calculated in the G to H Columns.I Summarized a "Simple Interest Calc" plus a Rate of Return Calc.Yes, this property returned a 2889% total ROI, an equivalent of a 161% ROI/YR over 18 Years and the Equivalent of a 21% Rate of Return (RoR).There are some things that weren't added to the Calculations such as Renovations (around $50k) and Positive Cash Flows (but it was Negative Cash Flow the 1st 3 years), rent Increases, Expense Increases, etc.We would need a much more comprehensive Spreadsheet to do all the calculations appropriately.Needless to say, this is a very BASIC analysis of a REAL purchase that I made.

We do not give our criteria per se, but do let applicants know that we do a comprehensive background screen including credit/criminal/eviction and verify income and past LL references.  

The 990-T would be specific to the single leveraged investment and not comprehensive for the IRA as a whole.The bottom line with UDFI is that if the cost of using leverage (in terms of taxation and tax preparation) does not diminish the return on investment in any significant fashion, and the resulting net after-UDFI return from the investment is superior to other non-leveraged investments, then the deal can make sense.

Your lender should provide you with a comprehensive package of requirements upfront.