If you can't figure it out, ask your agent for help. Should you decide to use the contingencies to get out of the deal, get yourself a lawyer. Agents cannot practice law, but will offer advice. You will need an attorney to execute a kill letter to make sure that you are legally protected.
Ian is right. Make sure you really do want out of this deal. Radon can be mitigated to a safe level fairly easily and inexpensively and an appraisal for $5K less than purchase price is not a big deal, unless it affects your mortgage commitment. Another appraisal might bring it in at the price you need, anyway.
If the sellers would correct the defects, and reduce the price $5K the question then becomes, "would you still buy the place?"