The property is financed at a local bank with a portfolio loan (because of some odd zoning that prevented us from using a conventional mortgage).

It ia possible to find a leak once they thaw.Weeks/months ago was the correct time to worry.Since this a is temporary (heat will be on by next year), use space heaters to thaw or prevent freezing if you can get power from a common area.I insulate pipes in semi-heated areas, and use heating cable covered in insulation wherever I have pipes in unheated areas.

You need a whole solution that prevents it from repeating.

Sort of.But.. if the contract prevents it there really is no way around it.

If your offer is complete with all required initials, any lender required 'verbiage' and/or SS addendums and updated proof of funds .. it will prevent delay's but might not make it go 'faster' per-say.

This prevents things like "the LL said my security deposit would be applied to my last months rent (no your SD is for damages and will be refunded AFTER the last months rent is paid and any repairs are deducted), "the W/D,fridge, stove... are mine not the previous LL's", "I signed for $500/mo rent but the LL said I only had to pay $400 as long as I mow the grass and do the snow removal" ect2) Now you need to know if the LL might have placed higher than market tenants using some sort of a teaser "no SD required" or " free first months rent (but higher than market rent for the remaining lease term)".

Maybe you have a minimum heat requirement that is intended to prevent frozen pipes; the fact that pipes froze would indicate a violation of such a clause / addendum.How easy would it be for you to actually collect assuming the tenant admits / concedes guilt in this matter?

Everything's negotiable and a lender might be willing to back off, but there is no built-in right for a borrower to prevent the lender exercising DOS by deeding back the property.

What kind of pitfalls have you experienced that have prevented closing?

Excessive talking is usually an attempt to prevent getting challenged on anything.Better Business Bureau is making money off accreditation.. but I would still take a look at the complaints.