Welcome. I'm not sure what all you have but I have a few suggestions I think might help you in your journey to a successful mini Reef. As I see your pretty proud of your little Bristle worm :).
A refractometer would be a very good investment. You can find them for around $50 on line. Be sure to look for one that say's it's an ATC. Automatic Temperture Control, this will allow you to make your Saltwater closer to the correct SG. Most keep there SG @ 1.023. You can use RO/DI water to calibrate it. Hydro's are plastic and have plastic moving parts, which overtime become caked with salt creep and give off false readings. Refractometer's are simple to use and in seconds you know right where your SG is at.
Buying a second heater or having a back up is almost a need. No heater is perfect & if one goes out it's best to have a back up on hand.
As far as test kit's go, ALL test kit's have a shelf life. Keep an eye out for that, it should be printed on the box somewhere. If you can't find that, Don't buy it. A trusted true and tried kit can be a life saver. I use Salifert or Elos test kits only. But that's the one's I've had the best luck with. They cost a little more, and there shelf life is stickered right on the box.
And my last peice of advise is, If you can keep the temp within 77-80*, the SG between 1.023 and 1.026, the ph close to 8.0, The calcium above 400 and the Alk somewhere inbetween 7.0 to 11.0 and Nitrites, Nitrates, Ammo @ zero, everything else should fall into line. It sounds like a lot to do, it's not really.
Oh and always use at least RO water if you can't use RO/DI water.
Best of luck and, remember their is no stupid question we were all there once :).