If I were you this is EXACTLY what I would do.
1. Since you are just starting I would do what you are doing now and do ALOT of research and reading before you dive headfirst (pat on the back for that.

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2. Use the live rock and the sandbed. That is always a good idea.
3. Get the biggest heater you can get your hands on. Reason being this: The larger the heater, the faster it will compensate for temperature drops in the tank. It will keep your water more stable. If you already have a 200 watt or so heater, then ok, 200 will work, but bigger is better. But if you havent already got one, surf the net for some monster heaters (I had 300 watt in mine and I wished it was bigger.) you can get them for fairly cheap. Get the biggest that your budget will allow. But remember, If you get one that is oversized the temperature setting on them wont be accurate (I.e to keep the tank at 78, you may have to set the heater on like 60 degrees.) Shoot for a temp of 76-78 degrees feirenheit for your tank. (I hate that word, I know its not spelled right.)
3. I dont really know much of the cpr skimmers, If the other guys (who are way smarter then me btw.) say they are good then cool. However, if you dont yet have a skimmer, read about the different models and their differences (venturi, countercurrent, etc.) and the advantages and disadvantages. (actually do this anyways

) Again in this department I would get the biggest freakin one you can get your hands on, dont skimp on this part it will save your ass in the future. This is a rule of thumb for future aquariums too.
4. Lights, I also agree with Magilla. Store your MH for now, but when you purchase future critters MAKE SURE that you do research before you buy them (dont ever buy anything without knowing what it is, though we are all guilty of it.) Make sure you know the lighting requirements, critters that need high light levels from the MH will not suvive on your strip lights. I would put the MH in the garage for this reason: It is one more hassle that you don't quite yet need, get going first and get your water up to par, and know what you are doing first, then worry about the light.
5. DO NOT use tap water, regardless. I say this for your warning because tap water (declorinized or not) usually sucks for a bunch of reasons. Even if you never have monster algae blooms using it, it is a pain because you dont ever know exactly what is in it or what you are dealing with. I cant afford an RO/DI unit. (reverse osmosis, Deionizer, they will filter all water to about 99.9% pure, something else for you to read up on

) And because I cant afford one, I buy it. You can buy it at your local grocery store or Wal-mart. Look at the label though, there is a difference between distilled and R/O. Pick up the water bottle and look at the label on the front, It will have in small print something that looks like: Filtered by-reverse osmosis, deionization, and UV sterilization. Something to that tune. As long as it says "reverse osmosis, deionization" that is what you need to get. It is cheap, about 60cents a gallon.
6. Water changes, water changes, water changes, water changes, WATER CHANGES. I cant stress it enough. Some people can get buy without them. (though I will never be one of those people.) Change as much water as frequently and consistantly as possible on a schedule so your animals can adapt. Here is how I handle mine: I went to wal-mart and bought a trash can that was about 13 gallons or so. Every thursday, I go to the store and pick up 10 gallons of the afore mentioned water. I take it home and fill up my trash can with all 10 gallons. I use oceanic salt for my changes, If I were you I would not mess with anything but Instant Ocean (the "REEF CRYSTALS" version, not the normal one with the clownfish on the front. Instant ocean, Reef crystals will say "reef crystals." on the front) or oceanic, not to say the other ones are bad, but these two have been tried a lot with a lot of success, especially instant ocean. Anyways, I use the salt and mix up the water to the desired salinity (you have to buy a hydrometer if you didnt already know. I recommend the deep six hydrometer. If you dont have one, then I can mail you one if you really need it, I have an extra. 1.020-1.023 is the magic number.) Ok back to topic. I mix the salt in the water, not the water in the salt. Let me repeat this; mix the salt in the water, not the water in the salt. (meaning pour the water first, then add the salt.) This is important, a extremely high salinity can cause calcium to parcipitate and lower your pH to death-on-contact levels. After I have the salt mixed up and it is all ready to go, I DO NOT add it yet. I put two small powerheads (Id mail you those if I had any extras.) In the trash can and run them with the bubbles turned on (the instructions will tell you how to do this, if you dont know.) I Let it aereate overnight. Friday after work I change 10 gallons out (using two 5 gallon buckets) and put the new 10 gallons in. I do this EVERY week like clockwork. I know it sounds like a lot of work, but it isnt. All in all it takes me about an hour to mix it (that includes trip-to-store time.) and about 15 minutes to siphon the water. Now, you don't need to change 10 gallons of water like me, I have a 55 gallon. But you can probably get away with 5 gallons or even 3. (10-20 percent of your total tank water.) But the key is: do it consistantly on a schedule or you are asking for it.
I hope that this helps, and i hope I didnt just confuse the hell out of you, I have a tendency to ramble. Anymore questions and we will be glad to help. Best of luck to ya bro!