I can go into a bit more detail here without cluttering a communal topic =). As I mentioned in your other post, I highly recommend investing in a good T5 tube. I use this one and it's fantastic
http://www.lightyourreptiles.com/22-t-5-ho-fixture-high-output-with-arcadia-d3-12-ho-bulb/ Lighting is incredibly important so I put that at the top of the budget and go from there.
There are other things that come with that kit that are not very good and in some cases can be harmful.
I would replace the sand and use a solid substrate. Non adhesive shelf liner, butcher paper, newspaper, or ceramic tile are good options because they can easily be replaced or sanitized and aren't likely to be ingested which can cause problems, especially for young dragons.
The 100w basking light should be OK but that really depends on the temperatures you're recording. This can vary from tank to tank due to a variety of factors. It's important to use a reliable thermometer to monitor the temps across the tank. The analog thermometers the kit comes with aren't very useful. You want to know the surface temps around the tank. An IR temp gun like this
https://www.amazon.com/Nubee-Temperature-Non-contact-Infrared-Thermometer/dp/B00CVHIJDK or a couple of digital thermometers with probes like this
https://www.amazon.com/dp/B0017N8W90/ are the way to go. You want to adjust the basking light so you have a basking surface temperature between about 100-110 and a gradient down to about 75-80 or so on the other side of the tank. This provides plenty of options for your dragon to move around and self regulate. They tend to want different temperatures at different points of the day.
You can try raising the basking light up using an adjustable lamp stand if it's too hot, or you could try moving to a higher wattage if it's too cool.This takes a bit of tweaking to get just right no matter the setup. Since you'll have a second dome available after replacing the compact
UVB light, you can put in a low wattage basking light if needed, or you could use a low wattage ceramic heat emitter which can be used as a night light.
You may not need any additional heat overnight so go based on your temp readings. If the temperatures stay above 65 in the tank overnight, it's fine. I find that my tank temps drop only on cold nights in the winter and even then I use a low wattage heat bulb to bump the temps only into the low 70s overnight.