WELCOME TO AA!!
Please do not cycle your tank with live animals.
All of the above is very sound advice. Your lighting need will depend on what type of corals you want to keep. On Mhs, if you have a deep tank, you might want to go with a higher Wattage for deeper water penetration. (I'll let the reffer folks help when you decide on what you really want).
Heaters: I prefer titanium, they won't break. I like my Finnex digital heaters.
Power Heads: I have a 125G that I use 4 SEIO 820s.
Test kit, for reef, I'm not sure, (reefers)?
Titanium grond probe.
I like to buy most of my stuff from drsfosterandsmith.com. They have great prices and don't charge extra for weight.
I agree, if you can do about 1.5-2Lbs of rock per gallon, you won't really need a filter. If you are looking to cut costs, use a mixture of base rock and some LR
That's about all I can think of, at the moment. Please feel free to chime in and add anything I missed.