geday from Australia

my dear 603.... I put a tank of (i think) B100 through her, no problems, a little less power.
Now I put some dino in her and i noticed the smell... under the hood check, the left (from driver's seat) side of the engine is wet with diesel.
The little shielded hoses that run from cylinder to cylinder- on the TOP of the head - are WET too. Wettest between cylinders in center of engine.
I haven't changed fuel filters for 3,000 miles. (tank filter at all)

Please excuse my ignorance.
What are those hoses?

Any theories on what's wrong?

When I replace any bio-rotted fuel hoses, what kind of hose should I buy?