Congress can and does override executive orders with legislation
<what is checks and balances
Congress can cut funding but as you pointed out yourself executive orders aren't fucking laws so they can't be overridden by laws. They're above the law and carried out as such.
The courts are also superior to EOs
This is technically true but only if a court is wants to challenge the order. No court wanted to challenge the bump-stock ban so it went into effect, but they did challenge his EO to ban muslims.
EOs are not what you think they are
You are the one denying that they have any power at all. Look up the bump-stock ban, talk to a local gunstore owner and tell him all this shit and he will laugh at you. The ban is in effect. I would hope the courts would challenge EO gun control but they haven't so far, so why would they now? Hmmm?