Query regarding resigning procedure with single permit

Hello all,

I have query regarding resignation process with new Single permit and joining in Belgium local company.

I'm currently staying in Brussels and holding Single permit. I got new offer and planning to resign my current company. My new company is ready to initiate blue card. Since with Single permit both WP and RP will be the same date could you tell me what will be the procedure to submit old SP and getting new SP?

I read somewhere that once my old employer cancels my work authorization my residence authority also terminates. Is that the case with same with SP also?

I read that blue card means it is single card for both work permit and residence permit. Does that mean once I get blue card I can discard my old single permit?

Please advise me.

Thanks,
Santosh