The lighting requirements really depends on what types of corals you intend to keep in the tank.
It looks like it is not a drilled tank and no room in the stand for a
sump so I am going to assume that you will not be using a sump at all. With that in mind you will want to find a nice hang on back protein
skimmer rated for close to double what your tank size is. While the skimmer may say "works for tanks up to 90 gallons" the reality is that it is not very efficient at cleaning the water in a 90 gallon tank.
For filtration, most
SW tanks use
live rock as the filter at a rate of about 1 lb of live rock per 1 gallon of tank. Then you use power heads to keep the water in the tank moving through the rocks in order to act use it as a filter. Commonly you want to push about 20-40x the tanks volume per hour. So for a 75g tank you want to be able to push 1500
GPH as a minimum.
For heating I would strongly suggest going with 2 or more heaters. The reasoning behind this being that if one goes down there is always a backup available to keep the tank heated. For a single 300 watt heater should have no problem keeping a tank that size warm so I would personally go with 2 200 watt heaters, placing one on each end of the tank.