Head gaskets do blow occasionally, especially on old cars. You have no way of telling when. He might ave driven it without coolant... The unbalanced wheel might have been him parking like an idiot and if the clutch is juddering after 6 months he can take it up with the garage where you had it installed.
If he was after a new car he shouldn't have bought it over ebay! Bought as seen!
If he does turn up at your house make him a cup of tea and if he turns nasty run back in and call the cops. If he rings to say when he'll be there just have a mate around conveniently...
It's all probably a load of hot air anyway
