Draw off cock is leaking, or leaking at the joint to the pipework. That is what needs fixing!
As for the boiler, if it's surface rust (probably), and not penetrating corrosion, then I doubt it's of concern, though obviously you want to prevent it getting worse. It depends whether that is essentially a decorative/electrical enclosure in which case even if it's rusted through, it doesn't matter that much, or if it's an integral part of how the boiler manages combustion/fresh air circulation in which case the casing condition is important. Get it serviced and get advice from the person doing the service, but if you sort the leak, then that will probably be the end of the matter.
I suppose it could be repainted, but there is an argument that it's better to see this kind of fault openly so the condition of the metal can be clearly seen, so may not be a good idea if that metal is not purely a decorative/electrical enclosure.
