Hi Dbmet,
Glad to have you aboard The Reef Tank!
The best beginning point for starting a saltwater tank is to get a good book. The Conscietious Marine Aquarist, by Robert Fenner is a good one that will cover just about everything and will be a good reference book for the future. John Tullock's, Natural Reef Aquariums, is another good one. Each runs about $25 online.
There are many different ways to set up a successful saltwater aquarium. Much depends on what your goals for the tank are: coral reef; fish only; species tank; etc. You indicate you want a fish only tank so you need to determine which fish you want to keep and consider their compatability with one another. A huge consideration is the size of the adult fish. A 58, IMHO, is too small for Tangs, Triggers, and most other large free-swimming fish. If you are interested in these type fish, a much larger tank would be necessary to support them as adults. An old rule of thumb says 1" of fish per 5 gallons but this is subject to many variables, such as fish body type, their eating habits, and the fish themselves.
Please read one or both of the books mentioned before making any purchases or hard decisions about your plan for this tank.
Just as a general suggestion for a 58 gal tank, a basic setup could include 60-90 lbs. of live rock; 4-6" deep sand bed; good skimmer (Manufacturer's ratings are usually very optimistic); 3-4 powerheads for circulaton; a sump for increased water volume and housing tank equipment; and a collection of miscellaneous equipment such as test kits; water filtration; etc.
As for the LFS tanks, those are display tanks that usually house fish for a short time; many LFS have central filtration systems and should not be considered as representational for a stand-alone home aquarium.
A DSB can be a very effective biofiltration system for any tank, including a FOWLR. They do take time to develop; about 6 months to support a very modest bioload and up to 18 months to fully develop. Some fish do feed on the substrate creatures so this is another issue in fish selection. These are generally covered in either of the two books.
Bear in mind that you will encounter many different opinions so it is important to read as much current books and articles as possible so you can make your own informed choices.
In addition to the books, here are some excellent websites with good information for starting up and maintaining a saltwater aquarium:
http://www.reefkeepers.org/faq/cache/33.html http://www.rshimek.com/reef/sediment.htm http://www.webring.org/cgi-bin/webring?ring=reeffaq;list http://www.hobbyschool.com/reef/
This is a very reading-intensive hobby as well as requiring lots of patience. That's all part of the challenge of learning and the best pathway to a successful aquarium.
Again, welcome to TRT!
Dick