NeveSSL
Got tubes?
I recommend to anyone to get a controller. The AquaController Jr. can do autotopoff, temp control (both heaters and/or fans), turn stuff on and off at the right times (main lights and sump lights), and all kinds of other stuff. Plus they keep up with your temp and pH, which is nice. Greatest part is that they're only about $270 I think for everything you would need from reefgeek.com.
Also, something that I don't think has been mentioned yet, IF you are an MTRC club member, you can get a discount at reefgeek on your lights and controller. The amount of the discount depends on the amount you spend, so if you bought your lights and controller at the same time, you could get a decent discount. I'd have to lookup again the exact amounts, though. I can't remember.
Do note, though, that this is only if you are an MTRC member.
I noticed you said you thought about putting sump money into the controller... dude, get a sump and wait on a controller or save up a bit more (since you're wanting to go slow anyway) and get both. A sump is a bit intimidating with drilling the glass and etc., etc., but its more than worth it. You get to put most of your ugly equipment in it plus other neat stuff (such as a refugium which can help big time with nutrient export using macro-algae such as chaeto).
I'm not 100% what you're asking on your lights question, but to attempt to answer it, you will want at least 4 48" T5HOs. I personally would recommend the IceCap retrofit kits at ReefGeek. However, if you're doing a 120g, I would highly recommend getting at least 6 T5HOs. I have 4 T5HOs over my 45g tall because its 12.5" wide. If I had a 120, I'd definitely be putting at least 6 over it considering how much wider it is (I think they're 24"?).
Just some thoughts.
If you're feeling overwhelmed by all of this, just take your time and STUDY! You can't study for every thing, but learning more about different tank setups and techniques can at least get you started in the right direction in your next setup and quite possibly save you a lot of frustration or at least make you happier with your setup.
Hope this helps!
Brandon
Also, something that I don't think has been mentioned yet, IF you are an MTRC club member, you can get a discount at reefgeek on your lights and controller. The amount of the discount depends on the amount you spend, so if you bought your lights and controller at the same time, you could get a decent discount. I'd have to lookup again the exact amounts, though. I can't remember.
Do note, though, that this is only if you are an MTRC member. I noticed you said you thought about putting sump money into the controller... dude, get a sump and wait on a controller or save up a bit more (since you're wanting to go slow anyway) and get both. A sump is a bit intimidating with drilling the glass and etc., etc., but its more than worth it. You get to put most of your ugly equipment in it plus other neat stuff (such as a refugium which can help big time with nutrient export using macro-algae such as chaeto).
I'm not 100% what you're asking on your lights question, but to attempt to answer it, you will want at least 4 48" T5HOs. I personally would recommend the IceCap retrofit kits at ReefGeek. However, if you're doing a 120g, I would highly recommend getting at least 6 T5HOs. I have 4 T5HOs over my 45g tall because its 12.5" wide. If I had a 120, I'd definitely be putting at least 6 over it considering how much wider it is (I think they're 24"?).
Just some thoughts.
If you're feeling overwhelmed by all of this, just take your time and STUDY! You can't study for every thing, but learning more about different tank setups and techniques can at least get you started in the right direction in your next setup and quite possibly save you a lot of frustration or at least make you happier with your setup.
Hope this helps!
Brandon
If you'd prefer to give MH's a try (which is what I assume you're referring to), then go for it! Just be prepared for high heat and high running costs (bulbs need to be replaced every 6-12 months). At the same time, they do seem to give better color to corals in my limited experience. 
