Yes. The sales agent will handle it for you.

old car if still keep (not selling) the ncd become 0%, coz 55% transferred to new car.

if old car policy not expired yet, example expiry date is october and u buy new car on july, recommended to go to counter (walk-in) of the insurance/takaful provider branch, top up the diff to old car policy (will be pro-rate), then they will issue a letter regarding that, bring the letter to new car insurance/takaful provider to transfer that 55%. easier if same provider.

usually (easiest way) is wait old car policy expired first, dont renew yet and go buy new car mentioned to sales agent to transfer the old car ncd.
after pay new car policy then only renew old car policy online.

Yes.
You can:
1) ask your SA to kowtim

2) contact your insurance company to "withdraw NCD". You will be asked to top up premium for old car. Your NCD can then be used for new car where you enjoy 55% for new car. The con of doing this is if your new car takes months to arrive and you withdraw ncd early, you rugi on old insurance

3) pay full premium for new car, then withdraw ncd + contact new insurance and get partial refund for new car insurance.