Your beardie is absolutely adorable and I think your tank looks very nice.
There are a few things I would like to comment on. First and most importantly..... you need to get a better thermometer. Unfortunately, the dial/stick-on type that you are using is only reading the ambient temps. It is very important to get direct basking spot temps.
You can use either a digital thermometer with a long wire and probe end or an infrared temperature gun. Walmart carries a great little digital therm. called AcuRite. It runs about $12 and can be found in the home thermometer section(not the pet section). Make sure to get one with a wire and probe end.
I also noticed your UVB is sitting on top of the screen top. The screens do block some of the UVB. You can either cut an opening in the screen top to expose the light or hang the fixture in the tank. Will you be getting a ReptiSUN 10 to replace the Zilla UVB?
I love the branches you have in Spike's tank. Just make sure that they are stable and cannot move. If they were to fall on your beardie... he could get injured or trapped under them.
About the Calcium and Multivitamin dusting... As a baby, your beardie only needs the calcium dusted on his feeders 5 x a week and the multivitamins dusted on his feeders the other 2 days. You don't want to oversupplement your little guy.
Other than that, I think you are doing a great job with Spike.