Do you have any fishtanks now? What sorts of fish have you kept?
I'll answer your questions one by one, best as I can:
1) The most important, should I trust wal-mart for tanks?
I've never had any problems with tanks I've gotten from Wal-Mart. However, the largest tank I've bought from them is a ten-gallon. Haven't had any troubles with it, though, and I've had it over a year.
2) Should I start with just a planted tank instead of venturing into saltwater suddenly?
I believe it's recommended that you have a fair bit of freshwater experience before you venture into saltwater. In addition to being rather expensive, saltwater also requires more time than freshwater. For example, a water change isn't just taking out water and adding new water - you have to make sure the water you're going to add is at the correct salinity and temperature.
3) The tank comes with just the hood, so what will I need to buy? UGF vs Biowheel? Lighting? - I want it 24 hours with a sort of night glow deal. and so on. I have no idea what I need.
I would go for a Biowheel filter or some other power/hang on back filter. I've used Whispers and have had no problems with them. As the name says, they're quiet. You could also go with a canister filter, but I don't know much about those, so I'll let somebody else comment on them. I think they are recommended if you want a heavily planted tank, though. I don't know about night-time lighting, so perhaps someone else can help you there. Check and see if the hood comes with light bulbs. If not, you'll have to get a couple. You'll probably need to 24" ones, but check on the box and see what it says. If you want to have a planted tank, you're going to have to add some more lighting, as what the tank comes with won't be enough for growing many live plants.
4) What chemicals will I need to keep the tank healthy?
If your tap water has chlorine in it, you will need some type of dechlorinator. I use Jungle's StartRight, but there are a lot of other brands out there. As long as it removes chlorine and chloramines, it should be fine. That should be all you need, unless you want to keep meds on hand, in case somebody gets sick. Oh, just remembered - you might want to get water testing kits. If you do, you'll want to make sure to get test for nitrite, nitrate, and ammonia. I think the Aquarium Pharmaceuticals Freshwater Master Test Kit now comes with a test for nitrate (it didn't when I bought it), as well as test for ammonia, nitrite, pH, kH, and the like.
Of course, you'll need fish food, but what sort of food you get depends on the kinds of fish you get. You'll have to get some sort of substrate for the tank. I prefer sand. If you're going to go for a planted tank, there's some special kind of substrate you can get to put under your sand or gravel, but I don't know what it's called. The Plants & Planted Tanks forum might have more information on that.
As far as fish go...it's up to you. Do you want one or two big, fairly aggressive fish, or would you prefer lots of smaller, more peaceful fish? Do you want a species tank? Do you want Cichlids? Is there a specific species you want? Check out the Fish Index and see if anything in their suits your fancy. I'm a big fan of Corys
If you don't already have fish, I recommend checking out the pinned articles on cycling a new tank (I think they're in the beginner forum). If you already have a fish tank set up, you can just take filter media from that one, transfer it to your new tank, and you're tank will be instantly cycled. However, it will only be cycled for about as many fish as you have in the filter you took the media from, so add new fish a few at a time to give the bacteria in the filter time to catch up. If you don't have a tank already set up, your local fish store may give you some gravel or filter media to help cycle your tank.
Hope that helps you out some!
Pamela
aka Married Lizard
