I have 30k expiring Asia Miles and need to redeem a ticket. Wanted to check if my understanding about award changes is correct before I call Asia Miles for the redemption.

I'll redeem a Y r/t ticket CGK-HKG on CX, which requires 35k miles.

If, in the future, I need to change it to CGK-HKG-NRT on CX, I can re-route the ticket, paying the fee of USD30, plus the incremental 10k miles (and increase in tax & fuel surcharge, if any). Is this right?

Two more questions regarding the new routing CGK-HKG-NRT:
1. Am I entitled to a free stopover at HKG?
2. If I reroute, I cannot change carriers, right? (e.g. the return NRT-CGK non-stop on JL, instead of via HKG on CX)