Item interactions with Gangplank barrels?

I'm just starting to learn GP, and am wondering how a few items interact with his barrels.

On-hit effects: Non-Tri Sheens: Energized Attacks: Weird Ones: and Lifesteal in general.

Don't worry, I'm not planning on building all these on him, but I would like to know the extent of his synergy with items. Thanks for any help you can provide!

Edit: Also, any other help/advice on Gangplank would be much appreciated as well. Thanks again!