absolutely, positively, 100% wrong!I'd have ball valves on the pipes to the sump for sure... how else would you be able to stop water coming in the overflows when you might need to service the sump? Also, IMO its better to have the return open 100% in a case like this, and then adjust the down flow to match.
Do NOT restrict the drains to the sump (without an additional emergency overflow drain)... unless you prefer the 'flood' upstairs instead of in the basement!