My friend, you need a test kit. Taking the water to your LFS to test is a pain, and an unnecessary waste of gas if you trek out to the LFS every time you should test. I use the API test kit and am moderately happy with it. The basic saltwater test kit is a good start, but you will also want to add a calcium, carbonate hardness, and phosphate test to the basic set. These aren't expensive, and you have the satisfaction in knowing
exactly what your parameters are at any given time of night or day.
I worry that your LFS is pushing stuff on you that you may not need yet. If your tank is just recently set up, you probably don't need much right now anyway. Chemicals like calcium and iodine are used by invertabrates and corals to build up their exoskeletons. Do you have any shrimp, crabs, or corals right now? You really should still be cycling the tank (in other words, no fishies and certainly no corals) right now, so I don't see that you would need a calcium supplement. Coraline algae will grow on its own anyway. Also, if your pH is low right now, your best bet is to do a water change first before you think about a buffer. You should be doing this anyway if you're cycling the tank.
I'm not trying to bust your derierre here..... Lord knows we ALL made mistakes when starting out, and, like everything else in the world, there is a degree of learning curve involved here. For your immediate situation, I strongly recommend you get the test kits I mentioned above. They're easy to use. And you should be testing at least twice a week -- I shoot for every third day. This way you will always know what's up, what's down, and what chemicals you will need to dose.
One final note: do NOT bother with the test strips. They are not accurate. Get the chemistry set....it's more effective, and fun!