Build the stand well just 40 gallons water along is 333#’s. Build solid !
Your planning helps and is good. Tank that size an “ATBA” will buy you some time with him being 4” now. Depending if male for sure and his DNA may only get 6-7 inches as adult. Look into used glass tanks or stock tanks to save money. Pet shops when remodeling put on sale very cheap older used tanks. You can offer him much more in a stock tank due to the wider sizes. Look in photo gallery for “Piggley’s pictures / videos on his home for ideas. He’s a little over 5” in a 150 gallon stock tank. Also use several price trackers to help watch sales. On stock tank’s look at tractor /farm supply store’s , much cheaper than at a big box store.
1: fixture's needs to have ceramic socket for the heat. Read up on UVB's and get one that does both UVA and UVb only a few out there does both ! Will only need one fixture then costing less and those type bulbs last longer saving money. I use mega ray, cost little more but when looking at total cost of others needing to be replaced every few months cost is small.
2: water conditioner for a beginner yes “prime” is a good one. If a adequate filter and use proper amount of carbon no drops would be needed. It removes chlorine and chloramine’s. But even the best carbon gets saturated with toxins and needs to be changed in 3-5 weeks. Until you understand that fully use the drops.
3: live plants // stay away from being a beginner , adds more maintenance , get water parameters , cycling down first then maybe add some down the road. But all will become a food source.
4: Getting an adult size setup at his size 4” will be cheaper in the long run. A 60 gallon with a ATBA would be good or a 90 gallon part full ( to prevent escape) with basking area in tank is also good. A 100 gallon rubbermaid stock tank is 1/4th the cost of glass tanks and would be a good size even part full to prevent escape and a floating basking area. Won’t have all those upgrades that get costly.
Read here:
http://www.redearslider.com/startup.htmlI'll be back from my vacation with the grandkids in a few days , will be able to help more then. Don't tell the kids I was online !