I'm afraid the crux of what you're asking is impossible for anybody to answer, because "is it worth it" is totally subjective.

You need to buy a new WoW key, plus expansions. You need to shell out for a second account every month. If you want the simplest "just turn it on and go" multiboxing solution, you might also want to buy Keyclone.

To some people, that's alot of cash up-front for something you really just want to use to make gold from.

The duo you're talking about don't synergise as well as other pairs would, but yes it's doable. There's lots of discussion around here talking about boxing melee classes with or without ranged classes.

In terms of exactly what dailies are multibox friendly, there's a very recent guide in this thread over here.

Hopefully that arms you with enough information to help you make your own decision.