Born again aquarium enthusiast needs help!

I've had this 30 hex Oceanic sitting around for a couple years (mainly
because I haven't had the time or money to maintain the hobby). I've been
out of the "loop" of aquariums for awhile and would like to get back into
it. I'm thinking setting this up as a cichlid tank eventually, but am still
unsure on which way I'll go.
The question I have is..this thing is pretty dirty, as it's been
collecting dust for awhile now..what is the best way to clean it? I figure
dish soap and water is fine just as long as I rinse it out good enough when
finished?
Currently I have a Penguin bio wheel power filter along with an
undergravel filter with a powerhead. I remember I was running this setup
before when it was setup as a marine tank and before that freshwater. It
seemed to work fine. Does this sound like a decent setup?
I guess that's all for now, but I'm sure I'll be back to ask more
questions as this progresses. It'll be good to get back into aquariums
again now that I can afford it

TIA for any info/help