Few questions

I am getting a russian from someone i work with who's kid doesnt want anymore.They have had it for 2 years and got it from a local pet store at 4ish inches. It was in a glass aquarium so i built a table out of coroplast that is 15" high. I am using cypress mulch and got a mercury vapor bulb. Im going to get a thermometer at home depot tomorrow and already have a temp gun. I am in the midwest so it cant stay outside all year. I have just a couple questions.

If i feed mazuri a couple times a week do i still need to add calcium supplements?

Is there somewhere I can order edible flowers from that delivers to the US? Torts r us does not

Do i just pray the bedding daily to keep the humidity or do i have to add water and mix it up?

Is slate ok to put as the stone under the basking light?

Her is a pic of the table so far. Just need some more mulch to put over the hide

Flowers?: www.tortoisesupply.com sells seed mixes and such.
Spray or water?: to start, add water, but to maintain humidity, you can spray.
Slate?: Perfecto, as long as it doesn’t get too hot.

Welcome to the forum!
Here's a couple useful threads when getting started.
https://www.tortoiseforum.org/threads/beginner-mistakes.45180/

https://www.tortoiseforum.org/threads/russian-tortoise-care-sheet.80698/

Looks like a nice enclosure. Adding some objects as sight barriers and decor will make it more interesting to your new tort. Fake or real (tort safe) plants, logs, pieces of wood, rocks, etc..
check the enclosure section if you need ideas.
Have fun getting to know your new tortoise!

One more thing...the mvb says it reccomends a deep dome light fixture. Does it really matter or can i use a standard dome?

Just waiting on my slate pieces to get here in a couple days