All I can say is that my partners 2011 car which has the same engine is still going strong after 215,000 miles, I change the oil & filter every 10,000 miles and only ever use a good quality synthetic oil, Shell Helix Professional AG. As long as you use the correct oil the timing chain should last the lifetime of the engine, unless the tensioner develops a fault. I don't think there's any adjustment possible, if the chain stretches excessively due to wear then the crankshaft and camshaft sprockets may also have worn out.
There are 2 chains in the engine, one that drives the high pressure injection pump from the crankshaft, and another that drives the camshafts from the injection pump sprocket. Each chain has it's own tensioner. It's looks to me like it would be an engine out job to replace the chains, so it would be worth getting the opinion of a trusty mechanic to figure out what the rattle might be.
The car still has the original water pump but I think that's driven off the auxiliary drive belt, not the timing chain, so it can be replaced without having to disturb the timing chain.
