Trying to understand the Cardano Staking Calculator

Hello Forum and Happy New Year! All the best to all for 2021!

I’m using the Cardano Staking Calculator in helping me understand the costs/rewards of running my own stake pool:

I’m using a Pledge of 100,000 ADA
I see the running cost fixed fee of 68 ADA (340 per Epoch)

What do the following mean?
Running costs of 24,820 ADA
Stake Pool Operation Rewards of 83,401.611480 ADA

Is the running costs an estimate of what it will cost me in ADA to run a node (running a Linux server 24x7)?
Is the estimated reward of my pool if I pledge 100,000 to be 83,410 ADA/year?

What assumptions is this calculator using? I’m still learning staking so I believe there is a minimum ADA my pool would need to have before I even have a chance of creating a block. Are these estimates the calculator provides if my pool was at 64,000,000 ADA in total?

I know it’s hard to determine what rewards might be when we need to run a server. Omitting that cost…is there a calculator estimate for me to use if I was to have my pledge and delegates total 1 million ADA in my pool or 10 million ADA in my pool…etc?

Thank you.