melted coil lead and top end rattle

hi I just bought a 2006 sy250 I got it has a couple of probs

the coil lead is melted on the head ,it has melted the rubber but not thru to the wires I have taped it up for now can I replace the lead or do I have to replace the coil as well ?

the top end has a rattle it seems worse when its cold idle ,doesn't seem that bad once warm .I will pull it down and inspect the barrel/piston this week 

it is a bit hard to start when its cold,cleaned the airbox had a lot of crap in there the filter was filthy  , cleaned the carb it had a lot of crap in there mostly in the choke, air screw is only 1/4 turn out ,replaced spark plug ,choke on takes anything up to 20 kicks when cold to start ,,once warm it starts first kick ,once warm leave it for 5 min and will take 3 kicks  , I don't no trials bikes at all but the spark is white but the spark seems very small {compared to a dirt bikes spark} I will check all the earths on the bike and sort the melted lead,

the exhaust is chocka block with crud I will attempt to burn it out this arvo not sure if that has anything to do with cold starting 

I'm totally new to trials had a life time on dirt bikes,i had my first day trials riding yesterday on this and its the most fun iv had on a bike in along time any help would be appreciated cheers