If you want a reef it is advisable to have around (for your tank) 35-40lb live rock minimum, and same goes for sand, 35-40lb of aragonite sand.Don't use playsand in a reef, it doesnt do any good for the tank and it will just cause problems, as it doesnt buffer the ph level for one and playsand doesnt add calcium to the water. PH and calcium are two of the most important things to consider besides salinity (which calcium contributes to actualy) in reef systems.
Fish/corals, everything depends on what you want, I could list a ton of fish that are reef safe, and I can list the requirements of many corals but it really all comes down to what you want to keep.
Lighting is important in reefs, as I'm sure you know, but the amount depends on the corals, some more some less, if you have SPS/LPS you want losts of light, others may not need as much. With the HQI light you should be alright with just about any coral that requires alot of light (some have other requirments) the ones that dont need much light may be hurt by the strength of it though, so try to place them where they are shaded a bit, or as deep in the tank as possible.
Water flow is also very important to consider in a reef some corals require high flow to keep them clean, bring them food and nutrients, or to keep little critters off or what ever it is they need, wile with others high flow will most certainly kill them almost litteraly tear their fleash off their bones so to speak. So you have to consider placement of your corals there as well, ones that like little flow place well away from the powerheads (or w/e you are using for flow) and the ones that like high flow place nearer to the stream. I wouldnt suggest placing corals directly infront of the powerhead even ones that like highflow, and the powerheads can put out quite a bit up close.
In the end with reefs there is a ton to consider, but once set up properly is one of the most rewarding systems available, and I highly recomend it haha. Just don't jump in as you said you are trying to avoid, or you may not get the results you were hoping for and risk alot of time and money.