Both are LOB (Liveaboard).... which meant they sail from S'pore on Fri eveing..... returning on Sun night (10pm+). For a better check on timing.... check with the dive operater.
As for distance.... both are in Malaysia and not easy to get to if you plan to go there yourself. And NO... I've haven't be there... mainly because I'm not too interested in Wreck Dive.
Do note that HMS Repulse and HMS Prince Of Wales (both famous WWII Wreck) are for TECH Divers only.
While Kuantan Wreck and 7 Skies wreck are suitable for most divers with some experience. You might get a chance to see a Guitar Ray at Kuantan Wreck.