sorry about your fishies
but first thigns first, why did they pass away? Had the tank been used with any medicines or chemicals in the past?
Good lighting is not a nesesity, but is always a good thing to have, and owuld be needed if you want to have a reef tank. There are many different options or highoutput (HO), very-high outpout(VHO) power compact (PC) florecent lighting. Or if you have the money metal hallids.
filtration: You arae also probably going to need better filtration. You do not need a sump or refugium, so it doesnt matter if your tank is drilled or not, but if you want to get one, they have hang on back overflows to get water out. You can have a hang on back filter, or some type of canister filter. Just something large and heavy deuty
skimmer. a protein skimmer is a good thing to have and is considered essential by many of the people on this site. It removes organic waste from the water before it is able to produce harmful chemicals like NH3 that will kill you fish and inverts.
Sand and base rock, live rock would be better because of the biological filtration it has. but it costs a lot more. But i recomend it anyways.
enough flow. On your iflter and skimmer, it will saay the gallons per hour (GPH) that flows through it. in a saltwater tank, you need to have lots of oxygen so the water must be flowing constantly. For a fish only tank, you want around 18X the amount of gallons your tank is. If you want a reef, you want somewhere around 22X. If you do not have enough with your skimmer or filter, powerheads can be purchased. These seimply sit in the tank suck up water, and then move more around. It is better to have you flow even spread out then have 500 GPH here and 500 GPH there.
I am assuming you have a heater since you had tropical fish before.
Pretty much everything will depend on what you want to keep... so... what do you want to keep?
good luck!