Do clerics need the material components to cast spells that require them when arcane spell casters use them? Such as 50gp of ruby dust for the Continual Flame spell?
Also, if someone casts Continual Flame on an object, does just one point flame or the entire object? So we'd get a flaming sword (without heat or fire damage I know). Thanks.
Yes to the first.
Up to you for the second.
Continual flame requires the ruby dust. A spell with a listing of M/DF in the Components line is a different story. See page 213 of the Core rules for the details.