In considering your options you must first consider a few important points, whihc include, but are not limited to the following: 1) are there contingencies in the Contract that you must meet that the seller may have the power to surreptitiously sabotage; 2) are there time constraints in the Contract, such as 45 days to get a mortgage commitment, whereby on day 46 the Seller is lying in wait, determined to cancel the Contract; 3) are you really inclined to sue the Seller whereby if you win, and...
I would strongly suggest you vacate for a number of reasons. It may violate the building code; if a new C/O is required, then you may be occupying a property which currently lacks a valid C/O which could render your insurance policy as being null and void and in some jurisdictions, occupying a property which lacks a valid C/O is both a civil and a ciminal offense. Also from a common sense perspective, you could be ingesting toxic fumes, dust and materials and finally, plain and simple: you...
It all depends upon how you are identified in title to the house on the Deed. if you are identified as a "joint tenant" you should be "entitled" to refinance. Will you have to "qualify"? Most certainly. Banks no longer give away money as in a few years past.
Section 275 of the Real Property Law requires that a Mortgagee discharge a mortgage of record within a certain time period, under the cloud of being monetarily penalized. Following is a link to the statute. It is an easy read:
There is no "typical amount", it would be measured by the true cost of the work that needs to be done, coupled with the costs attendant to the dismissal, together with the potential penalites that may be further assessed until the work has been fully completed; which is why one should avoid escrows for matters such as this, and instead require that the Seller complete all of this in advance of closing.
It won't affect your "title", so to speak, but it will inevitably affect your ability to get a Certificate of Continuing Occupancy from the local municipality in form that will allow for you to close and thereby convey title to the house.