Hi Mark,
Marine Projects' approach to securing babystay to the deck was not the best - basically the tang you see above the deck is fixed to a piece of approx 20mm diameter tube glassed into the underside of the deck. The wire you see is most likely a basic means of addressing this, but there are alternatives such as replacing the babystay with forward lower shrouds or glassing a stainless plate the width of the coach roof into the underside of the deck.
The deformation ahead of the mast step is quite possibly caused by damp getting into the timber core of the deck (should be hardwood under the mast). This sometimes arises when holes are drilled for cable penetration and not lined properly. You don't say how much deformation and the current owner is obviously living with it, but rectification involves cutting out the wood core and replacing it.
Whether either of these is a deal breaker is subjective - you're buying a fairly old boat. Perhaps the vendor may be willing to accept an offer in the light of your findings, both of which appear possible to live with in the short term and are fixable. Perhaps he believes his asking price already allows for these issues.
Peter.